use serde::{Deserialize, Serialize};

use crate::settings::SettingsService;

// ── domain types ─────────────────────────────────────────────────────────────

/// A single open tab that should be restored on next launch.
#[derive(Debug, Serialize, Deserialize, Clone)]
#[serde(rename_all = "camelCase")]
pub struct WorkspaceTab {
    pub connection_id: i64,
    pub protocol: String,
    pub position: i32,
}

/// The full workspace state persisted between sessions.
#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct WorkspaceSnapshot {
    pub tabs: Vec<WorkspaceTab>,
}

// ── service ───────────────────────────────────────────────────────────────────

const SNAPSHOT_KEY: &str = "workspace_snapshot";
const CLEAN_SHUTDOWN_KEY: &str = "clean_shutdown";

pub struct WorkspaceService {
    settings: SettingsService,
}

impl WorkspaceService {
    pub fn new(settings: SettingsService) -> Self {
        Self { settings }
    }

    /// Serialize `snapshot` to JSON and persist it via the settings store.
    pub fn save(&self, snapshot: &WorkspaceSnapshot) -> Result<(), String> {
        let json = serde_json::to_string(snapshot)
            .map_err(|e| format!("workspace::save: failed to serialize snapshot: {e}"))?;
        self.settings.set(SNAPSHOT_KEY, &json)
    }

    /// Load and deserialize the last saved workspace snapshot.
    ///
    /// Returns `None` if no snapshot has been saved yet or if deserialization
    /// fails (treated as a fresh start rather than a hard error).
    pub fn load(&self) -> Option<WorkspaceSnapshot> {
        let json = self.settings.get(SNAPSHOT_KEY)?;
        serde_json::from_str(&json)
            .map_err(|e| eprintln!("workspace::load: failed to deserialize snapshot: {e}"))
            .ok()
    }

    /// Record that the application is shutting down cleanly.
    ///
    /// Call this just before the Tauri window closes normally.  On the next
    /// startup, `was_clean_shutdown()` will return `true` and the crash-
    /// recovery path can be skipped.
    pub fn mark_clean_shutdown(&self) -> Result<(), String> {
        self.settings.set(CLEAN_SHUTDOWN_KEY, "true")
    }

    /// Returns `true` if the last session ended with a clean shutdown.
    ///
    /// Returns `false` (crash / dirty shutdown) when the key is absent, empty,
    /// or set to any value other than `"true"`.
    pub fn was_clean_shutdown(&self) -> bool {
        self.settings
            .get(CLEAN_SHUTDOWN_KEY)
            .map(|v| v == "true")
            .unwrap_or(false)
    }

    /// Remove the clean-shutdown flag.
    ///
    /// Call this at startup — immediately after reading `was_clean_shutdown()`.
    /// The flag is only valid for the single launch following the shutdown that
    /// wrote it; clearing it ensures a subsequent crash is detected correctly.
    pub fn clear_clean_shutdown(&self) -> Result<(), String> {
        self.settings.delete(CLEAN_SHUTDOWN_KEY)
    }
}