//! Session side of Settings, keyboard shortcut presets, auto-save and crash recovery.

use std::path::Path;

use crate::autosave::{self, Sentinel};
use crate::prefs::{PREFS_FILE, Prefs};
use crate::shortcuts::{Keymaps, SHORTCUTS_FILE, ShortcutTable, UiCommand};
use crate::{EngineError, Result, Session};

impl Session {
    /// Load settings and shortcut presets from the config store and apply them.
    pub fn load_settings(&mut self) {
        if let Some(c) = &self.config {
            if let Some(t) = c.read(PREFS_FILE) {
                self.prefs = Prefs::from_json(&t);
            }
            if let Some(t) = c.read(SHORTCUTS_FILE) {
                self.keymaps = Keymaps::from_json(&t);
            }
        }
        self.prefs_changed();
        self.shortcuts_changed();
    }

    /// Settings changed: apply what the engine owns (cache budgets) and tell frontends.
    pub fn prefs_changed(&mut self) {
        self.prefs.normalize();
        self.layer_cache.set_budget(self.prefs.layer_cache_bytes());
        self.footage.set_cache_budget(self.prefs.media_cache_bytes());
        // Fewer undo levels apply right away.
        let levels = self.prefs.general.undo_levels.max(1) as usize;
        if self.history.undo.len() > levels {
            let extra = self.history.undo.len() - levels;
            self.history.undo.drain(..extra);
        }
        self.prefs_revision += 1;
    }

    /// Write settings to the config store.
    pub fn save_prefs(&self) {
        if let Some(c) = &self.config
            && let Err(e) = c.write(PREFS_FILE, &self.prefs.to_json())
        {
            log::warn!("saving settings: {e}");
        }
    }

    /// Shortcut presets changed: rebuild the table and save them.
    pub fn shortcuts_changed(&mut self) {
        self.shortcut_table = std::sync::OnceLock::new();
        if let Some(c) = &self.config
            && let Err(e) = c.write(SHORTCUTS_FILE, &self.keymaps.to_json())
        {
            log::warn!("saving keyboard shortcuts: {e}");
        }
    }

    /// The frontend's own bindable commands (tools, timeline navigation…).
    pub fn set_ui_commands(&mut self, cmds: Vec<UiCommand>) {
        self.ui_commands = cmds;
        self.shortcut_table = std::sync::OnceLock::new();
    }

    /// The active shortcut preset resolved against every bindable command.
    pub fn shortcuts(&self) -> &ShortcutTable {
        self.shortcut_table.get_or_init(|| ShortcutTable::build(&self.keymaps, &self.ui_commands))
    }

    /// Remember a project in File ▸ Open Recent and in the crash-recovery sentinel.
    pub(crate) fn note_project_path(&mut self, path: &str) {
        self.prefs.push_recent(path);
        self.save_prefs();
        self.autosave = autosave::AutoSaveState { last: self.autosave.last, sentinel: self.autosave.sentinel, ..Default::default() };
        self.update_sentinel();
    }

    /// Refresh the crash-recovery sentinel (when one is active).
    pub fn update_sentinel(&self) {
        if let Some(c) = &self.config
            && self.autosave.sentinel
        {
            let s = Sentinel { pid: autosave::pid(), project: self.path.clone(), autosave: self.autosave.last_path.clone(), dirty: self.is_dirty() };
            autosave::update(c.as_ref(), &s);
        }
    }

    /// Fallback folder for auto-saves of untitled projects (next to the settings).
    pub fn default_autosave_root(&self) -> Option<std::path::PathBuf> {
        self.config.as_ref().and_then(|c| c.dir())
    }

    /// Write an auto-save now (whether or not the project is dirty). Returns its path.
    pub fn autosave_now(&mut self) -> Result<String> {
        let json = self.project.to_json();
        let root = self.default_autosave_root();
        let (path, slot) = autosave::write(&self.prefs, self.path.as_deref(), root.as_deref(), self.autosave.last_slot, &json)
            .map_err(|e| EngineError::Other(format!("auto-save failed: {e}")))?;
        let p = path.to_string_lossy().to_string();
        self.autosave.last_slot = Some(slot);
        self.autosave.saved_revision = Some(self.revision);
        self.autosave.last_path = Some(p.clone());
        self.update_sentinel();
        Ok(p)
    }

    /// Call periodically with wall-clock seconds: auto-saves a dirty project once the interval
    /// has passed since the last auto-save (or since the first call). Returns the written path.
    pub fn autosave_tick(&mut self, now: f64) -> Option<Result<String>> {
        let a = &self.prefs.auto_save;
        if !a.enabled {
            self.autosave.last = Some(now);
            return None;
        }
        let interval = a.interval_minutes.max(1) as f64 * 60.0;
        let last = *self.autosave.last.get_or_insert(now);
        if now - last < interval {
            return None;
        }
        self.autosave.last = Some(now);
        if !self.is_dirty() || self.autosave.saved_revision == Some(self.revision) || self.render_job.is_some() {
            return None;
        }
        if self.path.is_none() && self.prefs.auto_save.location != "custom" && self.default_autosave_root().is_none() {
            return None;
        }
        let r = self.autosave_now();
        if let Ok(p) = &r {
            self.toast(format!("Auto-saved {}", Path::new(p).file_name().map(|n| n.to_string_lossy().to_string()).unwrap_or_default()));
        }
        Some(r)
    }

    /// At launch: start crash recovery. Returns the previous run's state when it didn't exit
    /// cleanly (and the setting asks for it).
    pub fn begin_recovery(&mut self) -> Option<autosave::Recovery> {
        let c = self.config.clone()?;
        let r = autosave::begin(c.as_ref(), &self.prefs);
        self.autosave.sentinel = true;
        self.update_sentinel();
        r.filter(|_| self.prefs.startup.offer_crash_recovery)
    }

    /// Clean exit: remove the crash-recovery sentinel.
    pub fn end_recovery(&mut self) {
        if let Some(c) = &self.config
            && self.autosave.sentinel
        {
            autosave::end(c.as_ref());
            self.autosave.sentinel = false;
        }
    }
}