use regex::Regex;
use serde::{Deserialize, Serialize};
use std::{
    borrow::Cow,
    collections::{HashMap, HashSet},
    path::PathBuf,
    str::FromStr,
    time::Instant,
};

use crate::{
    app::{layout_manager::*, *},
    canvas::ColourScheme,
    constants::*,
    units::data_units::DataUnit,
    utils::error::{self, BottomError},
};

use typed_builder::*;

use layout_options::*;

pub mod layout_options;

use anyhow::{Context, Result};

#[derive(Clone, Debug, Default, Deserialize, Serialize)]
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>,
}

impl Config {
    pub fn get_config_as_bytes(&self) -> anyhow::Result<Vec<u8>> {
        let mut config_string: Vec<Cow<'_, str>> = Vec::default();

        // Top level
        config_string.push(CONFIG_TOP_HEAD.into());
        config_string.push(toml::to_string_pretty(self)?.into());

        Ok(config_string.concat().as_bytes().to_vec())
    }
}

#[derive(Clone, Debug, Default, Deserialize, Serialize, TypedBuilder)]
pub struct ConfigFlags {
    #[builder(default, setter(strip_option))]
    pub hide_avg_cpu: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub dot_marker: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub temperature_type: Option<String>,

    #[builder(default, setter(strip_option))]
    pub rate: Option<u64>,

    #[builder(default, setter(strip_option))]
    pub left_legend: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub current_usage: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub group_processes: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub case_sensitive: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub whole_word: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub regex: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub default_widget: Option<String>,

    #[builder(default, setter(strip_option))]
    pub basic: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub default_time_value: Option<u64>,

    #[builder(default, setter(strip_option))]
    pub time_delta: Option<u64>,

    #[builder(default, setter(strip_option))]
    pub autohide_time: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub hide_time: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub default_widget_type: Option<String>,

    #[builder(default, setter(strip_option))]
    pub default_widget_count: Option<u64>,

    #[builder(default, setter(strip_option))]
    pub use_old_network_legend: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub hide_table_gap: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub battery: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub disable_click: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub no_write: Option<bool>,

    // For built-in colour palettes.
    #[builder(default, setter(strip_option))]
    pub color: Option<String>,

    // This is a huge hack to enable hashmap functionality WITHOUT being able to serializing the field.
    // Basically, keep a hashmap in the struct, and convert to a vector every time.
    #[builder(default, setter(strip_option))]
    #[serde(skip)]
    pub search_case_enabled_widgets_map: Option<HashMap<u64, bool>>,

    #[builder(default, setter(strip_option))]
    pub search_case_enabled_widgets: Option<Vec<WidgetIdEnabled>>,

    #[builder(default, setter(strip_option))]
    #[serde(skip)]
    pub search_whole_word_enabled_widgets_map: Option<HashMap<u64, bool>>,

    #[builder(default, setter(strip_option))]
    pub search_whole_word_enabled_widgets: Option<Vec<WidgetIdEnabled>>,

    #[builder(default, setter(strip_option))]
    #[serde(skip)]
    pub search_regex_enabled_widgets_map: Option<HashMap<u64, bool>>,

    #[builder(default, setter(strip_option))]
    pub search_regex_enabled_widgets: Option<Vec<WidgetIdEnabled>>,

    #[builder(default, setter(strip_option))]
    pub mem_as_value: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub tree: Option<bool>,

    #[builder(default, setter(strip_option))]
    show_table_scroll_position: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub process_command: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub disable_advanced_kill: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub network_use_bytes: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub network_use_log: Option<bool>,

    #[builder(default, setter(strip_option))]
    pub network_use_binary_prefix: Option<bool>,
}

#[derive(Clone, Default, Debug, Deserialize, Serialize)]
pub struct WidgetIdEnabled {
    id: u64,
    enabled: bool,
}

impl WidgetIdEnabled {
    pub fn create_from_hashmap(hashmap: &HashMap<u64, bool>) -> Vec<WidgetIdEnabled> {
        hashmap
            .iter()
            .map(|(id, enabled)| WidgetIdEnabled {
                id: *id,
                enabled: *enabled,
            })
            .collect()
    }
}

#[derive(Clone, Debug, Default, Deserialize, Serialize)]
pub struct ConfigColours {
    pub table_header_color: Option<String>,
    pub all_cpu_color: Option<String>,
    pub avg_cpu_color: Option<String>,
    pub cpu_core_colors: Option<Vec<String>>,
    pub ram_color: Option<String>,
    pub swap_color: Option<String>,
    pub rx_color: Option<String>,
    pub tx_color: Option<String>,
    pub rx_total_color: Option<String>, // These only affect basic mode.
    pub tx_total_color: Option<String>, // These only affect basic mode.
    pub border_color: Option<String>,
    pub highlighted_border_color: Option<String>,
    pub disabled_text_color: Option<String>,
    pub text_color: Option<String>,
    pub selected_text_color: Option<String>,
    pub selected_bg_color: Option<String>,
    pub widget_title_color: Option<String>,
    pub graph_color: Option<String>,
    pub high_battery_color: Option<String>,
    pub medium_battery_color: Option<String>,
    pub low_battery_color: Option<String>,
}

impl ConfigColours {
    pub fn is_empty(&self) -> bool {
        if let Ok(serialized_string) = toml::to_string(self) {
            if !serialized_string.is_empty() {
                return false;
            }
        }

        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,
}

pub fn build_app(
    matches: &clap::ArgMatches<'static>, config: &mut Config, widget_layout: &BottomLayout,
    default_widget_id: u64, default_widget_type_option: &Option<BottomWidgetType>,
    config_path: Option<PathBuf>,
) -> Result<App> {
    use BottomWidgetType::*;
    let autohide_time = get_autohide_time(&matches, &config);
    let default_time_value = get_default_time_value(&matches, &config)
        .context("Update 'default_time_value' in your config file.")?;
    let use_basic_mode = get_use_basic_mode(&matches, &config);

    // For processes
    let is_grouped = get_app_grouping(matches, config);
    let is_case_sensitive = get_app_case_sensitive(matches, config);
    let is_match_whole_word = get_app_match_whole_word(matches, config);
    let is_use_regex = get_app_use_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, DiskWidgetState> = 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 = get_mem_as_value(matches, config);
    let is_default_tree = get_is_default_tree(matches, config);
    let is_default_command = get_is_default_process_command(matches, config);
    let is_advanced_kill = !get_is_advanced_kill_disabled(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 = get_network_use_binary_prefix(matches, config);

    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::init(default_time_value, autohide_timer),
                            );
                        }
                        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,
                                    // network_unit_type.clone(),
                                    // network_scale_type.clone(),
                                ),
                            );
                        }
                        Proc => {
                            proc_state_map.insert(
                                widget.widget_id,
                                ProcWidgetState::init(
                                    is_case_sensitive,
                                    is_match_whole_word,
                                    is_use_regex,
                                    is_grouped,
                                    show_memory_as_values,
                                    is_default_tree,
                                    is_default_command,
                                ),
                            );
                        }
                        Disk => {
                            disk_state_map.insert(widget.widget_id, DiskWidgetState::init());
                        }
                        Temp => {
                            temp_state_map.insert(widget.widget_id, TempWidgetState::init());
                        }
                        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 app_config_fields = AppConfigFields {
        update_rate_in_milliseconds: get_update_rate_in_milliseconds(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: get_use_dot(matches, config),
        left_legend: get_use_left_legend(matches, config),
        use_current_cpu_total: get_use_current_cpu_total(matches, config),
        use_basic_mode,
        default_time_value,
        time_interval: get_time_interval(matches, config)
            .context("Update 'time_delta' in your config file.")?,
        hide_time: get_hide_time(matches, config),
        autohide_time,
        use_old_network_legend: get_use_old_network_legend(matches, config),
        table_gap: if get_hide_table_gap(matches, config) {
            0
        } else {
            1
        },
        disable_click: get_disable_click(matches, config),
        // no_write: get_no_write(matches, config),
        no_write: false,
        show_table_scroll_position: get_show_table_scroll_position(matches, config),
        is_advanced_kill,
        network_scale_type,
        network_unit_type,
        network_use_binary_prefix,
    };

    let used_widgets = UsedWidgets {
        use_cpu: used_widget_set.get(&Cpu).is_some() || used_widget_set.get(&BasicCpu).is_some(),
        use_mem: used_widget_set.get(&Mem).is_some() || used_widget_set.get(&BasicMem).is_some(),
        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")?;

    // One more thing - we have to update the search settings of our proc_state_map, and create the hashmaps if needed!
    // Note that if you change your layout, this might not actually match properly... not sure if/where we should deal with that...
    if let Some(flags) = &mut config.flags {
        if flags.case_sensitive.is_none() && !matches.is_present("case_sensitive") {
            if let Some(search_case_enabled_widgets) = &flags.search_case_enabled_widgets {
                let mapping = HashMap::new();
                for widget in search_case_enabled_widgets {
                    if let Some(proc_widget) = proc_state_map.get_mut(&widget.id) {
                        proc_widget.process_search_state.is_ignoring_case = !widget.enabled;
                    }
                }
                flags.search_case_enabled_widgets_map = Some(mapping);
            }
        }

        if flags.whole_word.is_none() && !matches.is_present("whole_word") {
            if let Some(search_whole_word_enabled_widgets) =
                &flags.search_whole_word_enabled_widgets
            {
                let mapping = HashMap::new();
                for widget in search_whole_word_enabled_widgets {
                    if let Some(proc_widget) = proc_state_map.get_mut(&widget.id) {
                        proc_widget.process_search_state.is_searching_whole_word = widget.enabled;
                    }
                }
                flags.search_whole_word_enabled_widgets_map = Some(mapping);
            }
        }

        if flags.regex.is_none() && !matches.is_present("regex") {
            if let Some(search_regex_enabled_widgets) = &flags.search_regex_enabled_widgets {
                let mapping = HashMap::new();
                for widget in search_regex_enabled_widgets {
                    if let Some(proc_widget) = proc_state_map.get_mut(&widget.id) {
                        proc_widget.process_search_state.is_searching_with_regex = widget.enabled;
                    }
                }
                flags.search_regex_enabled_widgets_map = Some(mapping);
            }
        }
    }

    Ok(App::builder()
        .app_config_fields(app_config_fields)
        .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))
        .disk_state(DiskState::init(disk_state_map))
        .temp_state(TempState::init(temp_state_map))
        .battery_state(BatteryState::init(battery_state_map))
        .basic_table_widget_state(basic_table_widget_state)
        .current_widget(widget_map.get(&initial_widget_id).unwrap().clone()) // TODO: [UNWRAP] - many of the unwraps are fine (like this one) but do a once-over and/or switch to expect?
        .widget_map(widget_map)
        .used_widgets(used_widgets)
        .filters(DataFilters {
            disk_filter,
            mount_filter,
            temp_filter,
            net_filter,
        })
        .config(config.clone())
        .config_path(config_path)
        .build())
}

pub fn get_widget_layout(
    matches: &clap::ArgMatches<'static>, config: &Config,
) -> error::Result<(BottomLayout, u64, Option<BottomWidgetType>)> {
    let left_legend = get_use_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 get_use_basic_mode(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::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_in_milliseconds(
    matches: &clap::ArgMatches<'static>, config: &Config,
) -> error::Result<u64> {
    let update_rate_in_milliseconds = if let Some(update_rate) = matches.value_of("rate") {
        update_rate.parse::<u128>()?
    } else if let Some(flags) = &config.flags {
        if let Some(rate) = flags.rate {
            rate as u128
        } else {
            DEFAULT_REFRESH_RATE_IN_MILLISECONDS as u128
        }
    } else {
        DEFAULT_REFRESH_RATE_IN_MILLISECONDS as u128
    };

    if update_rate_in_milliseconds < 250 {
        return Err(BottomError::ConfigError(
            "set your update rate to be at least 250 milliseconds.".to_string(),
        ));
    } else if update_rate_in_milliseconds as u128 > std::u64::MAX as u128 {
        return Err(BottomError::ConfigError(
            "set your update rate to be at most unsigned INT_MAX.".to_string(),
        ));
    }

    Ok(update_rate_in_milliseconds as u64)
}

fn get_temperature(
    matches: &clap::ArgMatches<'static>, config: &Config,
) -> error::Result<data_harvester::temperature::TemperatureType> {
    if matches.is_present("fahrenheit") {
        return Ok(data_harvester::temperature::TemperatureType::Fahrenheit);
    } else if matches.is_present("kelvin") {
        return Ok(data_harvester::temperature::TemperatureType::Kelvin);
    } else if matches.is_present("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: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("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 get_use_dot(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("dot_marker") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(dot_marker) = flags.dot_marker {
            return dot_marker;
        }
    }
    false
}

fn get_use_left_legend(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("left_legend") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(left_legend) = flags.left_legend {
            return left_legend;
        }
    }

    false
}

fn get_use_current_cpu_total(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("current_usage") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(current_usage) = flags.current_usage {
            return current_usage;
        }
    }

    false
}

fn get_use_basic_mode(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("basic") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(basic) = flags.basic {
            return basic;
        }
    }

    false
}

fn get_default_time_value(
    matches: &clap::ArgMatches<'static>, config: &Config,
) -> error::Result<u64> {
    let default_time = if let Some(default_time_value) = matches.value_of("default_time_value") {
        default_time_value.parse::<u128>()?
    } else if let Some(flags) = &config.flags {
        if let Some(default_time_value) = flags.default_time_value {
            default_time_value as u128
        } else {
            DEFAULT_TIME_MILLISECONDS as u128
        }
    } else {
        DEFAULT_TIME_MILLISECONDS as u128
    };

    if default_time < 30000 {
        return Err(BottomError::ConfigError(
            "set your default value to be at least 30000 milliseconds.".to_string(),
        ));
    } else if default_time as u128 > STALE_MAX_MILLISECONDS as u128 {
        return Err(BottomError::ConfigError(format!(
            "set your default value to be at most {} milliseconds.",
            STALE_MAX_MILLISECONDS
        )));
    }

    Ok(default_time as u64)
}

fn get_time_interval(matches: &clap::ArgMatches<'static>, config: &Config) -> error::Result<u64> {
    let time_interval = if let Some(time_interval) = matches.value_of("time_delta") {
        time_interval.parse::<u128>()?
    } else if let Some(flags) = &config.flags {
        if let Some(time_interval) = flags.time_delta {
            time_interval as u128
        } else {
            TIME_CHANGE_MILLISECONDS as u128
        }
    } else {
        TIME_CHANGE_MILLISECONDS as u128
    };

    if time_interval < 1000 {
        return Err(BottomError::ConfigError(
            "set your time delta to be at least 1000 milliseconds.".to_string(),
        ));
    } else if time_interval > STALE_MAX_MILLISECONDS as u128 {
        return Err(BottomError::ConfigError(format!(
            "set your time delta to be at most {} milliseconds.",
            STALE_MAX_MILLISECONDS
        )));
    }

    Ok(time_interval as u64)
}

pub fn get_app_grouping(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("group") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(grouping) = flags.group_processes {
            return grouping;
        }
    }
    false
}

pub fn get_app_case_sensitive(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("case_sensitive") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(case_sensitive) = flags.case_sensitive {
            return case_sensitive;
        }
    }
    false
}

pub fn get_app_match_whole_word(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("whole_word") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(whole_word) = flags.whole_word {
            return whole_word;
        }
    }
    false
}

pub fn get_app_use_regex(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("regex") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(regex) = flags.regex {
            return regex;
        }
    }
    false
}

fn get_hide_time(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("hide_time") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(hide_time) = flags.hide_time {
            return hide_time;
        }
    }
    false
}

fn get_autohide_time(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("autohide_time") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(autohide_time) = flags.autohide_time {
            return autohide_time;
        }
    }

    false
}

fn get_default_widget_and_count(
    matches: &clap::ArgMatches<'static>, config: &Config,
) -> error::Result<(Option<BottomWidgetType>, u64)> {
    let widget_type = if let Some(widget_type) = matches.value_of("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.value_of("default_widget_count") {
        Some(widget_count.parse::<u128>()?)
    } else if let Some(flags) = &config.flags {
        flags
            .default_widget_count
            .map(|widget_count| widget_count as u128)
    } else {
        None
    };

    match (widget_type, widget_count) {
        (Some(widget_type), Some(widget_count)) => {
            if widget_count > std::u64::MAX as u128 {
                Err(BottomError::ConfigError(
                    "set your widget count to be at most unsigned INT_MAX.".to_string(),
                ))
            } else {
                Ok((Some(widget_type), widget_count as u64))
            }
        }
        (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))
    }
}

fn get_disable_click(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("disable_click") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(disable_click) = flags.disable_click {
            return disable_click;
        }
    }
    false
}

fn get_use_old_network_legend(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("use_old_network_legend") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(use_old_network_legend) = flags.use_old_network_legend {
            return use_old_network_legend;
        }
    }
    false
}

fn get_hide_table_gap(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("hide_table_gap") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(hide_table_gap) = flags.hide_table_gap {
            return hide_table_gap;
        }
    }
    false
}

fn get_use_battery(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("battery") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(battery) = flags.battery {
            return battery;
        }
    }
    false
}

#[allow(dead_code)]
fn get_no_write(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("no_write") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(no_write) = flags.no_write {
            return no_write;
        }
    }
    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: &clap::ArgMatches<'static>, config: &Config,
) -> error::Result<ColourScheme> {
    if let Some(color) = matches.value_of("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_mem_as_value(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("mem_as_value") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(mem_as_value) = flags.mem_as_value {
            return mem_as_value;
        }
    }
    false
}

fn get_is_default_tree(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("tree") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(tree) = flags.tree {
            return tree;
        }
    }
    false
}

fn get_show_table_scroll_position(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("show_table_scroll_position") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(show_table_scroll_position) = flags.show_table_scroll_position {
            return show_table_scroll_position;
        }
    }
    false
}

fn get_is_default_process_command(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("process_command") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(process_command) = flags.process_command {
            return process_command;
        }
    }
    false
}

fn get_is_advanced_kill_disabled(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("disable_advanced_kill") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(disable_advanced_kill) = flags.disable_advanced_kill {
            return disable_advanced_kill;
        }
    }
    false
}

fn get_network_unit_type(matches: &clap::ArgMatches<'static>, config: &Config) -> DataUnit {
    if matches.is_present("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: &clap::ArgMatches<'static>, config: &Config) -> AxisScaling {
    if matches.is_present("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_network_use_binary_prefix(matches: &clap::ArgMatches<'static>, config: &Config) -> bool {
    if matches.is_present("network_use_binary_prefix") {
        return true;
    } else if let Some(flags) = &config.flags {
        if let Some(network_use_binary_prefix) = flags.network_use_binary_prefix {
            return network_use_binary_prefix;
        }
    }
    false
}