use std::{
    borrow::Cow,
    convert::TryInto,
    str::FromStr,
    time::{Duration, Instant},
};

use clap::ArgMatches;
use hashbrown::{HashMap, HashSet};
use indexmap::IndexSet;
use layout_options::*;
use regex::Regex;
use serde::{Deserialize, Serialize};

#[cfg(feature = "battery")]
use starship_battery::Manager;

use crate::{
    app::{filter::Filter, layout_manager::*, *},
    canvas::{canvas_styling::CanvasStyling, ColourScheme},
    constants::*,
    utils::{
        data_units::DataUnit,
        error::{self, BottomError},
    },
    widgets::*,
};

pub mod layout_options;

pub mod process_columns;
use self::process_columns::ProcessConfig;

use anyhow::{Context, Result};

#[derive(Clone, Debug, Default, Deserialize)]
pub struct Config {
    pub flags: Option<ConfigFlags>,
    pub colors: Option<ConfigColours>,
    pub row: Option<Vec<Row>>,
    pub disk_filter: Option<IgnoreList>,
    pub mount_filter: Option<IgnoreList>,
    pub temp_filter: Option<IgnoreList>,
    pub net_filter: Option<IgnoreList>,
    pub processes: Option<ProcessConfig>,
}

#[derive(Clone, Debug, Deserialize, Serialize)]
#[serde(untagged)]
enum StringOrNum {
    String(String),
    Num(u64),
}

impl From<String> for StringOrNum {
    fn from(value: String) -> Self {
        StringOrNum::String(value)
    }
}

impl From<u64> for StringOrNum {
    fn from(value: u64) -> Self {
        StringOrNum::Num(value)
    }
}

#[derive(Clone, Debug, Default, Deserialize, Serialize)]
pub struct ConfigFlags {
    hide_avg_cpu: Option<bool>,
    dot_marker: Option<bool>,
    temperature_type: Option<String>,
    rate: Option<StringOrNum>,
    left_legend: Option<bool>,
    current_usage: Option<bool>,
    unnormalized_cpu: Option<bool>,
    group_processes: Option<bool>,
    case_sensitive: Option<bool>,
    whole_word: Option<bool>,
    regex: Option<bool>,
    basic: Option<bool>,
    default_time_value: Option<StringOrNum>,
    time_delta: Option<StringOrNum>,
    autohide_time: Option<bool>,
    hide_time: Option<bool>,
    default_widget_type: Option<String>,
    default_widget_count: Option<u64>,
    expanded_on_startup: Option<bool>,
    use_old_network_legend: Option<bool>,
    hide_table_gap: Option<bool>,
    battery: Option<bool>,
    disable_click: Option<bool>,
    no_write: Option<bool>,
    /// For built-in colour palettes.
    color: Option<String>,
    mem_as_value: Option<bool>,
    tree: Option<bool>,
    show_table_scroll_position: Option<bool>,
    process_command: Option<bool>,
    disable_advanced_kill: Option<bool>,
    network_use_bytes: Option<bool>,
    network_use_log: Option<bool>,
    network_use_binary_prefix: Option<bool>,
    enable_gpu_memory: Option<bool>,
    enable_cache_memory: Option<bool>,
    retention: Option<StringOrNum>,
}

#[derive(Clone, Debug, Default, Deserialize, Serialize)]
pub struct ConfigColours {
    pub table_header_color: Option<Cow<'static, str>>,
    pub all_cpu_color: Option<Cow<'static, str>>,
    pub avg_cpu_color: Option<Cow<'static, str>>,
    pub cpu_core_colors: Option<Vec<Cow<'static, str>>>,
    pub ram_color: Option<Cow<'static, str>>,
    #[cfg(not(target_os = "windows"))]
    pub cache_color: Option<Cow<'static, str>>,
    pub swap_color: Option<Cow<'static, str>>,
    pub arc_color: Option<Cow<'static, str>>,
    pub gpu_core_colors: Option<Vec<Cow<'static, str>>>,
    pub rx_color: Option<Cow<'static, str>>,
    pub tx_color: Option<Cow<'static, str>>,
    pub rx_total_color: Option<Cow<'static, str>>, // These only affect basic mode.
    pub tx_total_color: Option<Cow<'static, str>>, // These only affect basic mode.
    pub border_color: Option<Cow<'static, str>>,
    pub highlighted_border_color: Option<Cow<'static, str>>,
    pub disabled_text_color: Option<Cow<'static, str>>,
    pub text_color: Option<Cow<'static, str>>,
    pub selected_text_color: Option<Cow<'static, str>>,
    pub selected_bg_color: Option<Cow<'static, str>>,
    pub widget_title_color: Option<Cow<'static, str>>,
    pub graph_color: Option<Cow<'static, str>>,
    pub high_battery_color: Option<Cow<'static, str>>,
    pub medium_battery_color: Option<Cow<'static, str>>,
    pub low_battery_color: Option<Cow<'static, str>>,
}

impl ConfigColours {
    /// Returns `true` if there is a [`ConfigColours`] that is empty or there isn't one at all.
    pub fn is_empty(&self) -> bool {
        if let Ok(serialized_string) = toml_edit::ser::to_string(self) {
            return serialized_string.is_empty();
        }

        true
    }
}

/// Workaround as per https://github.com/serde-rs/serde/issues/1030
fn default_as_true() -> bool {
    true
}

#[derive(Clone, Debug, Default, Deserialize, Serialize)]
pub struct IgnoreList {
    #[serde(default = "default_as_true")]
    // TODO: Deprecate and/or rename, current name sounds awful.
    // Maybe to something like "deny_entries"?  Currently it defaults to a denylist anyways, so maybe "allow_entries"?
    pub is_list_ignored: bool,
    pub list: Vec<String>,
    #[serde(default = "bool::default")]
    pub regex: bool,
    #[serde(default = "bool::default")]
    pub case_sensitive: bool,
    #[serde(default = "bool::default")]
    pub whole_word: bool,
}

macro_rules! is_flag_enabled {
    ($flag_name:ident, $matches:expr, $config:expr) => {
        if $matches.get_flag(stringify!($flag_name)) {
            true
        } else if let Some(flags) = &$config.flags {
            flags.$flag_name.unwrap_or(false)
        } else {
            false
        }
    };

    ($cmd_flag:literal, $cfg_flag:ident, $matches:expr, $config:expr) => {
        if $matches.get_flag($cmd_flag) {
            true
        } else if let Some(flags) = &$config.flags {
            flags.$cfg_flag.unwrap_or(false)
        } else {
            false
        }
    };
}

pub fn build_app(
    matches: ArgMatches, config: Config, widget_layout: &BottomLayout, default_widget_id: u64,
    default_widget_type_option: &Option<BottomWidgetType>, styling: &CanvasStyling,
) -> Result<App> {
    use BottomWidgetType::*;

    // Since everything takes a reference, but we want to take ownership here to drop matches/config later...
    let matches = &matches;
    let config = &config;

    let retention_ms =
        get_retention(matches, config).context("Update `retention` in your config file.")?;
    let autohide_time = is_flag_enabled!(autohide_time, matches, config);
    let default_time_value = get_default_time_value(matches, config, retention_ms)
        .context("Update 'default_time_value' in your config file.")?;

    let use_basic_mode = is_flag_enabled!(basic, matches, config);
    let expanded_upon_startup = is_flag_enabled!(expanded_on_startup, matches, config);

    // For processes
    let is_grouped = is_flag_enabled!("group", group_processes, matches, config);
    let is_case_sensitive = is_flag_enabled!(case_sensitive, matches, config);
    let is_match_whole_word = is_flag_enabled!(whole_word, matches, config);
    let is_use_regex = is_flag_enabled!(regex, matches, config);

    let mut widget_map = HashMap::new();
    let mut cpu_state_map: HashMap<u64, CpuWidgetState> = HashMap::new();
    let mut mem_state_map: HashMap<u64, MemWidgetState> = HashMap::new();
    let mut net_state_map: HashMap<u64, NetWidgetState> = HashMap::new();
    let mut proc_state_map: HashMap<u64, ProcWidgetState> = HashMap::new();
    let mut temp_state_map: HashMap<u64, TempWidgetState> = HashMap::new();
    let mut disk_state_map: HashMap<u64, DiskTableWidget> = HashMap::new();
    let mut battery_state_map: HashMap<u64, BatteryWidgetState> = HashMap::new();

    let autohide_timer = if autohide_time {
        Some(Instant::now())
    } else {
        None
    };

    let mut initial_widget_id: u64 = default_widget_id;
    let mut initial_widget_type = Proc;
    let is_custom_layout = config.row.is_some();
    let mut used_widget_set = HashSet::new();

    let show_memory_as_values = is_flag_enabled!(mem_as_value, matches, config);
    let is_default_tree = is_flag_enabled!(tree, matches, config);
    let is_default_command = is_flag_enabled!(process_command, matches, config);
    let is_advanced_kill = !(is_flag_enabled!(disable_advanced_kill, matches, config));

    let network_unit_type = get_network_unit_type(matches, config);
    let network_scale_type = get_network_scale_type(matches, config);
    let network_use_binary_prefix = is_flag_enabled!(network_use_binary_prefix, matches, config);

    let proc_columns: Option<IndexSet<ProcWidgetColumn>> = {
        let columns = config
            .processes
            .as_ref()
            .and_then(|cfg| cfg.columns.clone());

        match columns {
            Some(columns) => {
                if columns.is_empty() {
                    None
                } else {
                    Some(IndexSet::from_iter(columns))
                }
            }
            None => None,
        }
    };

    let app_config_fields = AppConfigFields {
        update_rate: get_update_rate(matches, config)
            .context("Update 'rate' in your config file.")?,
        temperature_type: get_temperature(matches, config)
            .context("Update 'temperature_type' in your config file.")?,
        show_average_cpu: get_show_average_cpu(matches, config),
        use_dot: is_flag_enabled!(dot_marker, matches, config),
        left_legend: is_flag_enabled!(left_legend, matches, config),
        use_current_cpu_total: is_flag_enabled!(current_usage, matches, config),
        unnormalized_cpu: is_flag_enabled!(unnormalized_cpu, matches, config),
        use_basic_mode,
        default_time_value,
        time_interval: get_time_interval(matches, config, retention_ms)
            .context("Update 'time_delta' in your config file.")?,
        hide_time: is_flag_enabled!(hide_time, matches, config),
        autohide_time,
        use_old_network_legend: is_flag_enabled!(use_old_network_legend, matches, config),
        table_gap: u16::from(!(is_flag_enabled!(hide_table_gap, matches, config))),
        disable_click: is_flag_enabled!(disable_click, matches, config),
        enable_gpu_memory: get_enable_gpu_memory(matches, config),
        enable_cache_memory: get_enable_cache_memory(matches, config),
        show_table_scroll_position: is_flag_enabled!(show_table_scroll_position, matches, config),
        is_advanced_kill,
        network_scale_type,
        network_unit_type,
        network_use_binary_prefix,
        retention_ms,
    };

    let table_config = ProcTableConfig {
        is_case_sensitive,
        is_match_whole_word,
        is_use_regex,
        show_memory_as_values,
        is_command: is_default_command,
    };

    for row in &widget_layout.rows {
        for col in &row.children {
            for col_row in &col.children {
                for widget in &col_row.children {
                    widget_map.insert(widget.widget_id, widget.clone());
                    if let Some(default_widget_type) = &default_widget_type_option {
                        if !is_custom_layout || use_basic_mode {
                            match widget.widget_type {
                                BasicCpu => {
                                    if let Cpu = *default_widget_type {
                                        initial_widget_id = widget.widget_id;
                                        initial_widget_type = Cpu;
                                    }
                                }
                                BasicMem => {
                                    if let Mem = *default_widget_type {
                                        initial_widget_id = widget.widget_id;
                                        initial_widget_type = Cpu;
                                    }
                                }
                                BasicNet => {
                                    if let Net = *default_widget_type {
                                        initial_widget_id = widget.widget_id;
                                        initial_widget_type = Cpu;
                                    }
                                }
                                _ => {
                                    if *default_widget_type == widget.widget_type {
                                        initial_widget_id = widget.widget_id;
                                        initial_widget_type = widget.widget_type.clone();
                                    }
                                }
                            }
                        }
                    }

                    used_widget_set.insert(widget.widget_type.clone());

                    match widget.widget_type {
                        Cpu => {
                            cpu_state_map.insert(
                                widget.widget_id,
                                CpuWidgetState::new(
                                    &app_config_fields,
                                    default_time_value,
                                    autohide_timer,
                                    styling,
                                ),
                            );
                        }
                        Mem => {
                            mem_state_map.insert(
                                widget.widget_id,
                                MemWidgetState::init(default_time_value, autohide_timer),
                            );
                        }
                        Net => {
                            net_state_map.insert(
                                widget.widget_id,
                                NetWidgetState::init(default_time_value, autohide_timer),
                            );
                        }
                        Proc => {
                            let mode = if is_grouped {
                                ProcWidgetMode::Grouped
                            } else if is_default_tree {
                                ProcWidgetMode::Tree {
                                    collapsed_pids: Default::default(),
                                }
                            } else {
                                ProcWidgetMode::Normal
                            };

                            proc_state_map.insert(
                                widget.widget_id,
                                ProcWidgetState::new(
                                    &app_config_fields,
                                    mode,
                                    table_config,
                                    styling,
                                    &proc_columns,
                                ),
                            );
                        }
                        Disk => {
                            disk_state_map.insert(
                                widget.widget_id,
                                DiskTableWidget::new(&app_config_fields, styling),
                            );
                        }
                        Temp => {
                            temp_state_map.insert(
                                widget.widget_id,
                                TempWidgetState::new(&app_config_fields, styling),
                            );
                        }
                        Battery => {
                            battery_state_map
                                .insert(widget.widget_id, BatteryWidgetState::default());
                        }
                        _ => {}
                    }
                }
            }
        }
    }

    let basic_table_widget_state = if use_basic_mode {
        Some(match initial_widget_type {
            Proc | Disk | Temp => BasicTableWidgetState {
                currently_displayed_widget_type: initial_widget_type,
                currently_displayed_widget_id: initial_widget_id,
                widget_id: 100,
                left_tlc: None,
                left_brc: None,
                right_tlc: None,
                right_brc: None,
            },
            _ => BasicTableWidgetState {
                currently_displayed_widget_type: Proc,
                currently_displayed_widget_id: DEFAULT_WIDGET_ID,
                widget_id: 100,
                left_tlc: None,
                left_brc: None,
                right_tlc: None,
                right_brc: None,
            },
        })
    } else {
        None
    };

    let use_mem = used_widget_set.get(&Mem).is_some() || used_widget_set.get(&BasicMem).is_some();
    let used_widgets = UsedWidgets {
        use_cpu: used_widget_set.get(&Cpu).is_some() || used_widget_set.get(&BasicCpu).is_some(),
        use_mem,
        use_cache: use_mem && get_enable_cache_memory(matches, config),
        use_gpu: use_mem && get_enable_gpu_memory(matches, config),
        use_net: used_widget_set.get(&Net).is_some() || used_widget_set.get(&BasicNet).is_some(),
        use_proc: used_widget_set.get(&Proc).is_some(),
        use_disk: used_widget_set.get(&Disk).is_some(),
        use_temp: used_widget_set.get(&Temp).is_some(),
        use_battery: used_widget_set.get(&Battery).is_some(),
    };

    let disk_filter =
        get_ignore_list(&config.disk_filter).context("Update 'disk_filter' in your config file")?;
    let mount_filter = get_ignore_list(&config.mount_filter)
        .context("Update 'mount_filter' in your config file")?;
    let temp_filter =
        get_ignore_list(&config.temp_filter).context("Update 'temp_filter' in your config file")?;
    let net_filter =
        get_ignore_list(&config.net_filter).context("Update 'net_filter' in your config file")?;

    let states = AppWidgetStates {
        cpu_state: CpuState::init(cpu_state_map),
        mem_state: MemState::init(mem_state_map),
        net_state: NetState::init(net_state_map),
        proc_state: ProcState::init(proc_state_map),
        temp_state: TempState::init(temp_state_map),
        disk_state: DiskState::init(disk_state_map),
        battery_state: BatteryState::init(battery_state_map),
        basic_table_widget_state,
    };

    let current_widget = widget_map.get(&initial_widget_id).unwrap().clone();
    let filters = DataFilters {
        disk_filter,
        mount_filter,
        temp_filter,
        net_filter,
    };
    let is_expanded = expanded_upon_startup && !use_basic_mode;

    Ok(App::new(
        app_config_fields,
        states,
        widget_map,
        current_widget,
        used_widgets,
        filters,
        is_expanded,
    ))
}

pub fn get_widget_layout(
    matches: &ArgMatches, config: &Config,
) -> error::Result<(BottomLayout, u64, Option<BottomWidgetType>)> {
    let left_legend = is_flag_enabled!(left_legend, matches, config);

    let (default_widget_type, mut default_widget_count) =
        get_default_widget_and_count(matches, config)?;
    let mut default_widget_id = 1;

    let bottom_layout = if is_flag_enabled!(basic, matches, config) {
        default_widget_id = DEFAULT_WIDGET_ID;

        BottomLayout::init_basic_default(get_use_battery(matches, config))
    } else {
        let ref_row: Vec<Row>; // Required to handle reference
        let rows = match &config.row {
            Some(r) => r,
            None => {
                // This cannot (like it really shouldn't) fail!
                ref_row = toml_edit::de::from_str::<Config>(if get_use_battery(matches, config) {
                    DEFAULT_BATTERY_LAYOUT
                } else {
                    DEFAULT_LAYOUT
                })?
                .row
                .unwrap();
                &ref_row
            }
        };

        let mut iter_id = 0; // A lazy way of forcing unique IDs *shrugs*
        let mut total_height_ratio = 0;

        let mut ret_bottom_layout = BottomLayout {
            rows: rows
                .iter()
                .map(|row| {
                    row.convert_row_to_bottom_row(
                        &mut iter_id,
                        &mut total_height_ratio,
                        &mut default_widget_id,
                        &default_widget_type,
                        &mut default_widget_count,
                        left_legend,
                    )
                })
                .collect::<error::Result<Vec<_>>>()?,
            total_row_height_ratio: total_height_ratio,
        };

        // Confirm that we have at least ONE widget left - if not, error out!
        if iter_id > 0 {
            ret_bottom_layout.get_movement_mappings();
            // debug!("Bottom layout: {:#?}", ret_bottom_layout);

            ret_bottom_layout
        } else {
            return Err(error::BottomError::ConfigError(
                "please have at least one widget under the '[[row]]' section.".to_string(),
            ));
        }
    };

    Ok((bottom_layout, default_widget_id, default_widget_type))
}

fn get_update_rate(matches: &ArgMatches, config: &Config) -> error::Result<u64> {
    let update_rate = if let Some(update_rate) = matches.get_one::<String>("rate") {
        try_parse_ms(update_rate)?
    } else if let Some(flags) = &config.flags {
        if let Some(rate) = &flags.rate {
            match rate {
                StringOrNum::String(s) => try_parse_ms(s)?,
                StringOrNum::Num(n) => *n,
            }
        } else {
            DEFAULT_REFRESH_RATE_IN_MILLISECONDS
        }
    } else {
        DEFAULT_REFRESH_RATE_IN_MILLISECONDS
    };

    if update_rate < 250 {
        return Err(BottomError::ConfigError(
            "set your update rate to be at least 250 ms.".to_string(),
        ));
    }

    Ok(update_rate)
}

fn get_temperature(
    matches: &ArgMatches, config: &Config,
) -> error::Result<data_harvester::temperature::TemperatureType> {
    if matches.get_flag("fahrenheit") {
        return Ok(data_harvester::temperature::TemperatureType::Fahrenheit);
    } else if matches.get_flag("kelvin") {
        return Ok(data_harvester::temperature::TemperatureType::Kelvin);
    } else if matches.get_flag("celsius") {
        return Ok(data_harvester::temperature::TemperatureType::Celsius);
    } else if let Some(flags) = &config.flags {
        if let Some(temp_type) = &flags.temperature_type {
            // Give lowest priority to config.
            return match temp_type.as_str() {
                "fahrenheit" | "f" => Ok(data_harvester::temperature::TemperatureType::Fahrenheit),
                "kelvin" | "k" => Ok(data_harvester::temperature::TemperatureType::Kelvin),
                "celsius" | "c" => Ok(data_harvester::temperature::TemperatureType::Celsius),
                _ => Err(BottomError::ConfigError(format!(
                    "\"{}\" is an invalid temperature type, use \"<kelvin|k|celsius|c|fahrenheit|f>\".",
                    temp_type
                ))),
            };
        }
    }
    Ok(data_harvester::temperature::TemperatureType::Celsius)
}

/// Yes, this function gets whether to show average CPU (true) or not (false)
fn get_show_average_cpu(matches: &ArgMatches, config: &Config) -> bool {
    if matches.get_flag("hide_avg_cpu") {
        return false;
    } else if let Some(flags) = &config.flags {
        if let Some(avg_cpu) = flags.hide_avg_cpu {
            return !avg_cpu;
        }
    }

    true
}

fn try_parse_ms(s: &str) -> error::Result<u64> {
    if let Ok(val) = humantime::parse_duration(s) {
        Ok(val.as_millis().try_into()?)
    } else if let Ok(val) = s.parse::<u64>() {
        Ok(val)
    } else {
        Err(BottomError::ConfigError(
            "could not parse as a valid 64-bit unsigned integer or a human time".to_string(),
        ))
    }
}

fn get_default_time_value(
    matches: &ArgMatches, config: &Config, retention_ms: u64,
) -> error::Result<u64> {
    let default_time =
        if let Some(default_time_value) = matches.get_one::<String>("default_time_value") {
            try_parse_ms(default_time_value)?
        } else if let Some(flags) = &config.flags {
            if let Some(default_time_value) = &flags.default_time_value {
                match default_time_value {
                    StringOrNum::String(s) => try_parse_ms(s)?,
                    StringOrNum::Num(n) => *n,
                }
            } else {
                DEFAULT_TIME_MILLISECONDS
            }
        } else {
            DEFAULT_TIME_MILLISECONDS
        };

    if default_time < 30000 {
        return Err(BottomError::ConfigError(
            "set your default value to be at least 30s.".to_string(),
        ));
    } else if default_time > retention_ms {
        return Err(BottomError::ConfigError(format!(
            "set your default value to be at most {}.",
            humantime::Duration::from(Duration::from_millis(retention_ms))
        )));
    }

    Ok(default_time)
}

fn get_time_interval(
    matches: &ArgMatches, config: &Config, retention_ms: u64,
) -> error::Result<u64> {
    let time_interval = if let Some(time_interval) = matches.get_one::<String>("time_delta") {
        try_parse_ms(time_interval)?
    } else if let Some(flags) = &config.flags {
        if let Some(time_interval) = &flags.time_delta {
            match time_interval {
                StringOrNum::String(s) => try_parse_ms(s)?,
                StringOrNum::Num(n) => *n,
            }
        } else {
            TIME_CHANGE_MILLISECONDS
        }
    } else {
        TIME_CHANGE_MILLISECONDS
    };

    if time_interval < 1000 {
        return Err(BottomError::ConfigError(
            "set your time delta to be at least 1s.".to_string(),
        ));
    } else if time_interval > retention_ms {
        return Err(BottomError::ConfigError(format!(
            "set your time delta to be at most {}.",
            humantime::Duration::from(Duration::from_millis(retention_ms))
        )));
    }

    Ok(time_interval)
}

fn get_default_widget_and_count(
    matches: &ArgMatches, config: &Config,
) -> error::Result<(Option<BottomWidgetType>, u64)> {
    let widget_type = if let Some(widget_type) = matches.get_one::<String>("default_widget_type") {
        let parsed_widget = widget_type.parse::<BottomWidgetType>()?;
        if let BottomWidgetType::Empty = parsed_widget {
            None
        } else {
            Some(parsed_widget)
        }
    } else if let Some(flags) = &config.flags {
        if let Some(widget_type) = &flags.default_widget_type {
            let parsed_widget = widget_type.parse::<BottomWidgetType>()?;
            if let BottomWidgetType::Empty = parsed_widget {
                None
            } else {
                Some(parsed_widget)
            }
        } else {
            None
        }
    } else {
        None
    };

    let widget_count = if let Some(widget_count) = matches.get_one::<String>("default_widget_count")
    {
        Some(widget_count.parse::<u128>()?)
    } else if let Some(flags) = &config.flags {
        flags
            .default_widget_count
            .map(|widget_count| widget_count.into())
    } else {
        None
    };

    match (widget_type, widget_count) {
        (Some(widget_type), Some(widget_count)) => {
            let widget_count = widget_count.try_into().map_err(|_| BottomError::ConfigError(
                "set your widget count to be at most unsigned INT_MAX.".to_string()
            ))?;
            Ok((Some(widget_type), widget_count))
        }
        (Some(widget_type), None) => Ok((Some(widget_type), 1)),
        (None, Some(_widget_count)) =>  Err(BottomError::ConfigError(
            "cannot set 'default_widget_count' by itself, it must be used with 'default_widget_type'.".to_string(),
        )),
        (None, None) => Ok((None, 1))
    }
}

#[allow(unused_variables)]
fn get_use_battery(matches: &ArgMatches, config: &Config) -> bool {
    #[cfg(feature = "battery")]
    {
        if let Ok(battery_manager) = Manager::new() {
            if let Ok(batteries) = battery_manager.batteries() {
                if batteries.count() == 0 {
                    return false;
                }
            }
        }

        if matches.get_flag("battery") {
            return true;
        } else if let Some(flags) = &config.flags {
            if let Some(battery) = flags.battery {
                return battery;
            }
        }
    }

    false
}

#[allow(unused_variables)]
fn get_enable_gpu_memory(matches: &ArgMatches, config: &Config) -> bool {
    #[cfg(feature = "gpu")]
    {
        if matches.get_flag("enable_gpu_memory") {
            return true;
        } else if let Some(flags) = &config.flags {
            if let Some(enable_gpu_memory) = flags.enable_gpu_memory {
                return enable_gpu_memory;
            }
        }
    }

    false
}

#[allow(unused_variables)]
fn get_enable_cache_memory(matches: &ArgMatches, config: &Config) -> bool {
    #[cfg(not(target_os = "windows"))]
    {
        if matches.get_flag("enable_cache_memory") {
            return true;
        } else if let Some(flags) = &config.flags {
            if let Some(enable_cache_memory) = flags.enable_cache_memory {
                return enable_cache_memory;
            }
        }
    }

    false
}

fn get_ignore_list(ignore_list: &Option<IgnoreList>) -> error::Result<Option<Filter>> {
    if let Some(ignore_list) = ignore_list {
        let list: Result<Vec<_>, _> = ignore_list
            .list
            .iter()
            .map(|name| {
                let escaped_string: String;
                let res = format!(
                    "{}{}{}{}",
                    if ignore_list.whole_word { "^" } else { "" },
                    if ignore_list.case_sensitive {
                        ""
                    } else {
                        "(?i)"
                    },
                    if ignore_list.regex {
                        name
                    } else {
                        escaped_string = regex::escape(name);
                        &escaped_string
                    },
                    if ignore_list.whole_word { "$" } else { "" },
                );

                Regex::new(&res)
            })
            .collect();

        Ok(Some(Filter {
            list: list?,
            is_list_ignored: ignore_list.is_list_ignored,
        }))
    } else {
        Ok(None)
    }
}

pub fn get_color_scheme(matches: &ArgMatches, config: &Config) -> error::Result<ColourScheme> {
    if let Some(color) = matches.get_one::<String>("color") {
        // Highest priority is always command line flags...
        return ColourScheme::from_str(color);
    } else if let Some(colors) = &config.colors {
        if !colors.is_empty() {
            // Then, give priority to custom colours...
            return Ok(ColourScheme::Custom);
        } else if let Some(flags) = &config.flags {
            // Last priority is config file flags...
            if let Some(color) = &flags.color {
                return ColourScheme::from_str(color);
            }
        }
    } else if let Some(flags) = &config.flags {
        // Last priority is config file flags...
        if let Some(color) = &flags.color {
            return ColourScheme::from_str(color);
        }
    }

    // And lastly, the final case is just "default".
    Ok(ColourScheme::Default)
}

fn get_network_unit_type(matches: &ArgMatches, config: &Config) -> DataUnit {
    if matches.get_flag("network_use_bytes") {
        return DataUnit::Byte;
    } else if let Some(flags) = &config.flags {
        if let Some(network_use_bytes) = flags.network_use_bytes {
            if network_use_bytes {
                return DataUnit::Byte;
            }
        }
    }

    DataUnit::Bit
}

fn get_network_scale_type(matches: &ArgMatches, config: &Config) -> AxisScaling {
    if matches.get_flag("network_use_log") {
        return AxisScaling::Log;
    } else if let Some(flags) = &config.flags {
        if let Some(network_use_log) = flags.network_use_log {
            if network_use_log {
                return AxisScaling::Log;
            }
        }
    }

    AxisScaling::Linear
}

fn get_retention(matches: &ArgMatches, config: &Config) -> error::Result<u64> {
    const DEFAULT_RETENTION_MS: u64 = 600 * 1000; // Keep 10 minutes of data.

    if let Some(retention) = matches.get_one::<String>("retention") {
        try_parse_ms(retention)
    } else if let Some(flags) = &config.flags {
        if let Some(retention) = &flags.retention {
            Ok(match retention {
                StringOrNum::String(s) => try_parse_ms(s)?,
                StringOrNum::Num(n) => *n,
            })
        } else {
            Ok(DEFAULT_RETENTION_MS)
        }
    } else {
        Ok(DEFAULT_RETENTION_MS)
    }
}

#[cfg(test)]
mod test {
    use clap::ArgMatches;

    use super::{get_color_scheme, get_time_interval, get_widget_layout, Config};
    use crate::{
        app::App,
        canvas::canvas_styling::CanvasStyling,
        options::{
            get_default_time_value, get_retention, get_update_rate, try_parse_ms, ConfigFlags,
        },
    };

    #[test]
    fn verify_try_parse_ms() {
        let a = "100s";
        let b = "100";
        let c = "1 min";
        let d = "1 hour 1 min";

        assert_eq!(try_parse_ms(a), Ok(100 * 1000));
        assert_eq!(try_parse_ms(b), Ok(100));
        assert_eq!(try_parse_ms(c), Ok(60 * 1000));
        assert_eq!(try_parse_ms(d), Ok(3660 * 1000));

        let a_bad = "1 test";
        let b_bad = "-100";

        assert!(try_parse_ms(a_bad).is_err());
        assert!(try_parse_ms(b_bad).is_err());
    }

    #[test]
    fn matches_human_times() {
        let config = Config::default();
        let app = crate::args::build_app();

        {
            let app = app.clone();
            let delta_args = vec!["btm", "--time_delta", "2 min"];
            let matches = app.get_matches_from(delta_args);

            assert_eq!(
                get_time_interval(&matches, &config, 60 * 60 * 1000),
                Ok(2 * 60 * 1000)
            );
        }

        {
            let default_time_args = vec!["btm", "--default_time_value", "300s"];
            let matches = app.get_matches_from(default_time_args);

            assert_eq!(
                get_default_time_value(&matches, &config, 60 * 60 * 1000),
                Ok(5 * 60 * 1000)
            );
        }
    }

    #[test]
    fn matches_number_times() {
        let config = Config::default();
        let app = crate::args::build_app();

        {
            let app = app.clone();
            let delta_args = vec!["btm", "--time_delta", "120000"];
            let matches = app.get_matches_from(delta_args);

            assert_eq!(
                get_time_interval(&matches, &config, 60 * 60 * 1000),
                Ok(2 * 60 * 1000)
            );
        }

        {
            let default_time_args = vec!["btm", "--default_time_value", "300000"];
            let matches = app.get_matches_from(default_time_args);

            assert_eq!(
                get_default_time_value(&matches, &config, 60 * 60 * 1000),
                Ok(5 * 60 * 1000)
            );
        }
    }

    #[test]
    fn config_human_times() {
        let app = crate::args::build_app();
        let matches = app.get_matches_from(["btm"]);

        let mut config = Config::default();
        let flags = ConfigFlags {
            time_delta: Some("2 min".to_string().into()),
            default_time_value: Some("300s".to_string().into()),
            rate: Some("1s".to_string().into()),
            retention: Some("10m".to_string().into()),
            ..Default::default()
        };

        config.flags = Some(flags);

        assert_eq!(
            get_time_interval(&matches, &config, 60 * 60 * 1000),
            Ok(2 * 60 * 1000)
        );

        assert_eq!(
            get_default_time_value(&matches, &config, 60 * 60 * 1000),
            Ok(5 * 60 * 1000)
        );

        assert_eq!(get_update_rate(&matches, &config), Ok(1000));

        assert_eq!(get_retention(&matches, &config), Ok(600000));
    }

    #[test]
    fn config_number_times_as_string() {
        let app = crate::args::build_app();
        let matches = app.get_matches_from(["btm"]);

        let mut config = Config::default();
        let flags = ConfigFlags {
            time_delta: Some("120000".to_string().into()),
            default_time_value: Some("300000".to_string().into()),
            rate: Some("1000".to_string().into()),
            retention: Some("600000".to_string().into()),
            ..Default::default()
        };

        config.flags = Some(flags);

        assert_eq!(
            get_time_interval(&matches, &config, 60 * 60 * 1000),
            Ok(2 * 60 * 1000)
        );

        assert_eq!(
            get_default_time_value(&matches, &config, 60 * 60 * 1000),
            Ok(5 * 60 * 1000)
        );

        assert_eq!(get_update_rate(&matches, &config), Ok(1000));

        assert_eq!(get_retention(&matches, &config), Ok(600000));
    }

    #[test]
    fn config_number_times_as_num() {
        let app = crate::args::build_app();
        let matches = app.get_matches_from(["btm"]);

        let mut config = Config::default();
        let flags = ConfigFlags {
            time_delta: Some(120000.into()),
            default_time_value: Some(300000.into()),
            rate: Some(1000.into()),
            retention: Some(600000.into()),
            ..Default::default()
        };

        config.flags = Some(flags);

        assert_eq!(
            get_time_interval(&matches, &config, 60 * 60 * 1000),
            Ok(2 * 60 * 1000)
        );

        assert_eq!(
            get_default_time_value(&matches, &config, 60 * 60 * 1000),
            Ok(5 * 60 * 1000)
        );

        assert_eq!(get_update_rate(&matches, &config), Ok(1000));

        assert_eq!(get_retention(&matches, &config), Ok(600000));
    }

    fn create_app(config: Config, matches: ArgMatches) -> App {
        let (layout, id, ty) = get_widget_layout(&matches, &config).unwrap();
        let styling =
            CanvasStyling::new(get_color_scheme(&matches, &config).unwrap(), &config).unwrap();

        super::build_app(matches, config, &layout, id, &ty, &styling).unwrap()
    }

    // TODO: There's probably a better way to create clap options AND unify together to avoid the possibility of
    // typos/mixing up. Use proc macros to unify on one struct?
    #[test]
    fn verify_cli_options_build() {
        let app = crate::args::build_app();

        let default_app = {
            let app = app.clone();
            let config = Config::default();
            let matches = app.get_matches_from([""]);

            create_app(config, matches)
        };

        // Skip battery since it's tricky to test depending on the platform/features we're testing with.
        let skip = ["help", "version", "celsius", "battery"];

        for arg in app.get_arguments().collect::<Vec<_>>() {
            let arg_name = arg
                .get_long_and_visible_aliases()
                .unwrap()
                .first()
                .unwrap()
                .to_owned();

            if !arg.get_action().takes_values() && !skip.contains(&arg_name) {
                let arg = format!("--{arg_name}");

                let arguments = vec!["btm", &arg];
                let app = app.clone();
                let config = Config::default();
                let matches = app.get_matches_from(arguments);

                let testing_app = create_app(config, matches);

                if (default_app.app_config_fields == testing_app.app_config_fields)
                    && default_app.is_expanded == testing_app.is_expanded
                    && default_app
                        .states
                        .proc_state
                        .widget_states
                        .iter()
                        .zip(testing_app.states.proc_state.widget_states.iter())
                        .all(|(a, b)| (a.1.test_equality(b.1)))
                {
                    panic!("failed on {arg_name}");
                }
            }
        }
    }
}