//! Plugins configuration metadata
use std::borrow::Borrow;
use std::collections::HashMap;
use std::fs;
use std::path::{Path, PathBuf};
use thiserror::Error;

use serde::{Deserialize, Serialize};
use url::Url;

use super::layout::{RunPlugin, RunPluginLocation};
#[cfg(not(target_family = "wasm"))]
use crate::consts::ASSET_MAP;
pub use crate::data::PluginTag;
use crate::errors::prelude::*;

use std::collections::BTreeMap;
use std::fmt;

/// Used in the config struct for plugin metadata
#[derive(Clone, PartialEq, Deserialize, Serialize)]
pub struct PluginsConfig(pub HashMap<PluginTag, PluginConfig>);

impl fmt::Debug for PluginsConfig {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut stable_sorted = BTreeMap::new();
        for (plugin_tag, plugin_config) in self.0.iter() {
            stable_sorted.insert(plugin_tag, plugin_config);
        }
        write!(f, "{:#?}", stable_sorted)
    }
}

impl PluginsConfig {
    pub fn new() -> Self {
        Self(HashMap::new())
    }
    pub fn from_data(data: HashMap<PluginTag, PluginConfig>) -> Self {
        PluginsConfig(data)
    }

    /// Get plugin config from run configuration specified in layout files.
    pub fn get(&self, run: impl Borrow<RunPlugin>) -> Option<PluginConfig> {
        let run = run.borrow();
        match &run.location {
            RunPluginLocation::File(path) => Some(PluginConfig {
                path: path.clone(),
                run: PluginType::Pane(None),
                _allow_exec_host_cmd: run._allow_exec_host_cmd,
                location: run.location.clone(),
            }),
            RunPluginLocation::Zellij(tag) => self.0.get(tag).cloned().map(|plugin| PluginConfig {
                _allow_exec_host_cmd: run._allow_exec_host_cmd,
                ..plugin
            }),
        }
    }

    pub fn iter(&self) -> impl Iterator<Item = &PluginConfig> {
        self.0.values()
    }

    /// Merges two PluginConfig structs into one PluginConfig struct
    /// `other` overrides the PluginConfig of `self`.
    pub fn merge(&self, other: Self) -> Self {
        let mut plugin_config = self.0.clone();
        plugin_config.extend(other.0);
        Self(plugin_config)
    }
}

impl Default for PluginsConfig {
    fn default() -> Self {
        PluginsConfig(HashMap::new())
    }
}

/// Plugin metadata
#[derive(Clone, Debug, PartialEq, Eq, Hash, Deserialize, Serialize)]
pub struct PluginConfig {
    /// Path of the plugin, see resolve_wasm_bytes for resolution semantics
    pub path: PathBuf,
    /// Plugin type
    pub run: PluginType,
    /// Allow command execution from plugin
    pub _allow_exec_host_cmd: bool,
    /// Original location of the
    pub location: RunPluginLocation,
}

impl PluginConfig {
    /// Resolve wasm plugin bytes for the plugin path and given plugin directory.
    ///
    /// If zellij was built without the 'disable_automatic_asset_installation' feature, builtin
    /// plugins (Starting with 'zellij:' in the layout file) are loaded directly from the
    /// binary-internal asset map. Otherwise:
    ///
    /// Attempts to first resolve the plugin path as an absolute path, then adds a ".wasm"
    /// extension to the path and resolves that, finally we use the plugin directory joined with
    /// the path with an appended ".wasm" extension. So if our path is "tab-bar" and the given
    /// plugin dir is "/home/bob/.zellij/plugins" the lookup chain will be this:
    ///
    /// ```bash
    ///   /tab-bar
    ///   /tab-bar.wasm
    /// ```
    ///
    pub fn resolve_wasm_bytes(&self, plugin_dir: &Path) -> Result<Vec<u8>> {
        let err_context =
            |err: std::io::Error, path: &PathBuf| format!("{}: '{}'", err, path.display());

        // Locations we check for valid plugins
        let paths_arr = [
            &self.path,
            &self.path.with_extension("wasm"),
            &plugin_dir.join(&self.path).with_extension("wasm"),
        ];
        // Throw out dupes, because it's confusing to read that zellij checked the same plugin
        // location multiple times. Do NOT sort the vector here, because it will break the lookup!
        let mut paths = paths_arr.to_vec();
        paths.dedup();

        // This looks weird and usually we would handle errors like this differently, but in this
        // case it's helpful for users and developers alike. This way we preserve all the lookup
        // errors and can report all of them back. We must initialize `last_err` with something,
        // and since the user will only get to see it when loading a plugin failed, we may as well
        // spell it out right here.
        let mut last_err: Result<Vec<u8>> = Err(anyhow!("failed to load plugin from disk"));
        for path in paths {
            // Check if the plugin path matches an entry in the asset map. If so, load it directly
            // from memory, don't bother with the disk.
            #[cfg(not(target_family = "wasm"))]
            if !cfg!(feature = "disable_automatic_asset_installation") && self.is_builtin() {
                let asset_path = PathBuf::from("plugins").join(path);
                if let Some(bytes) = ASSET_MAP.get(&asset_path) {
                    log::debug!("Loaded plugin '{}' from internal assets", path.display());

                    if plugin_dir.join(path).with_extension("wasm").exists() {
                        log::info!(
                            "Plugin '{}' exists in the 'PLUGIN DIR' at '{}' but is being ignored",
                            path.display(),
                            plugin_dir.display()
                        );
                    }

                    return Ok(bytes.to_vec());
                }
            }

            // Try to read from disk
            match fs::read(&path) {
                Ok(val) => {
                    log::debug!("Loaded plugin '{}' from disk", path.display());
                    return Ok(val);
                },
                Err(err) => {
                    last_err = last_err.with_context(|| err_context(err, &path));
                },
            }
        }

        // Not reached if a plugin is found!
        #[cfg(not(target_family = "wasm"))]
        if self.is_builtin() {
            // Layout requested a builtin plugin that wasn't found
            let plugin_path = self.path.with_extension("wasm");

            if cfg!(feature = "disable_automatic_asset_installation")
                && ASSET_MAP.contains_key(&PathBuf::from("plugins").join(&plugin_path))
            {
                return Err(ZellijError::BuiltinPluginMissing {
                    plugin_path,
                    plugin_dir: plugin_dir.to_owned(),
                    source: last_err.unwrap_err(),
                })
                .context("failed to load a plugin");
            } else {
                return Err(ZellijError::BuiltinPluginNonexistent {
                    plugin_path,
                    source: last_err.unwrap_err(),
                })
                .context("failed to load a plugin");
            }
        }

        return last_err;
    }

    /// Sets the tab index inside of the plugin type of the run field.
    pub fn set_tab_index(&mut self, tab_index: usize) {
        match self.run {
            PluginType::Pane(..) => {
                self.run = PluginType::Pane(Some(tab_index));
            },
            PluginType::Headless => {},
        }
    }

    pub fn is_builtin(&self) -> bool {
        matches!(self.location, RunPluginLocation::Zellij(_))
    }
}

/// Type of the plugin. Defaults to Pane.
#[derive(Clone, Debug, PartialEq, Deserialize, Serialize, Hash, Eq)]
#[serde(rename_all = "kebab-case")]
pub enum PluginType {
    // TODO: A plugin with output that's cloned across every pane in a tab, or across the entire
    // application might be useful
    // Tab
    // Static
    /// Starts immediately when Zellij is started and runs without a visible pane
    Headless,
    /// Runs once per pane declared inside a layout file
    Pane(Option<usize>), // tab_index
}

impl Default for PluginType {
    fn default() -> Self {
        Self::Pane(None)
    }
}

#[derive(Error, Debug, PartialEq)]
pub enum PluginsConfigError {
    #[error("Duplication in plugin tag names is not allowed: '{}'", String::from(.0.clone()))]
    DuplicatePlugins(PluginTag),
    #[error("Failed to parse url: {0:?}")]
    InvalidUrl(#[from] url::ParseError),
    #[error("Only 'file:' and 'zellij:' url schemes are supported for plugin lookup. '{0}' does not match either.")]
    InvalidUrlScheme(Url),
    #[error("Could not find plugin at the path: '{0:?}'")]
    InvalidPluginLocation(PathBuf),
}