//! Top-level mutable application state (`AppStateRest`) and the transcript
//! display type it owns.
//!
//! `AppStateRest` is the single source-of-truth struct mutated in-place from
//! `actions/mod.rs` and `controller/input.rs`; every other module reads it.

use std::collections::VecDeque;
use std::path::PathBuf;
use std::sync::{Arc, Mutex};
use tokio::sync::RwLock;

use super::misc::{DirCache, InputState, MiscState, ScrollState};
use super::runtime::{SessionRuntime, TurnEvent};
use super::types::{Origin, Toast, TranscriptCache};
use crate::app::lsp::LspManager;
use crate::app::mcp::manager::McpManager;
use crate::app::workflow::engine::WorkflowEngine;
use crate::model::app_config::AppConfig;
use crate::model::editlog::EditLog;
use crate::model::settings::Settings;

/// A single transcript entry rendered in the TUI chat pane.
#[derive(Debug, Clone, PartialEq)]
pub struct ChatMessageDisplay {
    pub role: crate::dto::chat::message::Role,
    pub content: String,
    pub timestamp: i64,
}

impl ChatMessageDisplay {
    /// Build a display entry, stamping it with the current time.
    pub fn new(role: crate::dto::chat::message::Role, content: String) -> Self {
        ChatMessageDisplay {
            role,
            content,
            timestamp: chrono::Utc::now().timestamp_millis(),
        }
    }
}

/// The single source-of-truth state struct for the entire application.
///
/// Mutated in-place from two locations: `actions/mod.rs` (`apply_action`)
/// and `controller/input.rs` (key event handlers). Read-only from every
/// other module.
#[derive(Clone)]
pub struct AppStateRest {

    pub settings: Settings,
    pub app_config: AppConfig,
    pub workspace_roots: Vec<PathBuf>,
    pub session_id: String,
    pub session_dir: PathBuf,
    pub memory_dir: PathBuf,
    pub worktrees_dir: PathBuf,
    pub dir_cache: Arc<RwLock<DirCache>>,
    pub edit_log: EditLog,
    pub session_runtime: Option<SessionRuntime>,
    pub sessions: Vec<crate::model::session::Session>,
    pub transcript_cache: TranscriptCache,
    pub scroll: ScrollState,
    pub input: InputState,
    pub misc: MiscState,
    pub turn_events: Arc<Mutex<VecDeque<TurnEvent>>>,
    pub turn_in_flight: Arc<Mutex<bool>>,
    pub abort_flag: Arc<std::sync::atomic::AtomicBool>,
    pub workflow_engine: WorkflowEngine,
    pub mcp_manager: McpManager,
    pub lsp_manager: Arc<Mutex<LspManager>>,
    /// Shared queue: provisioner thread pushes status updates,
    /// drained into toasts on each Tick.
    pub lsp_provision_msgs: Arc<Mutex<VecDeque<String>>>,
    pub dirty: bool,
    pub quit: bool,
}

impl AppStateRest {
    /// Construct the initial application state for a session.
    ///
    /// Flow: load settings/config -> derive download/worktree dirs from
    /// `memory_dir`'s parent -> derive `session_id` from the session dir's
    /// file name -> build the sub-state structs.
    ///
    /// Why: falls back to `memory_dir` itself (with a warning) when it has
    /// no parent, and to an empty session id when the dir name can't be
    /// read, so construction never fails.
    pub fn new(workspace_roots: Vec<PathBuf>, session_dir: PathBuf, memory_dir: PathBuf) -> Self {
        let settings = Settings::load();
        let app_config = AppConfig::load();
        let worktrees_dir = memory_dir.parent().unwrap_or_else(|| {
            tracing::warn!("[state] memory_dir '{}' has no parent, using it for worktrees", memory_dir.display());
            &memory_dir
        }).join("worktrees");
        let dir_cache = DirCache::new();
        let session_id = session_dir
            .file_name()
            .map(|n| n.to_string_lossy().to_string())
            .unwrap_or_else(|| {
                tracing::warn!("[state] session_dir has no file_name component, using empty session_id");
                String::new()
            });
        let mut state = AppStateRest {

            settings,
            app_config,
            workspace_roots,
            session_id,
            session_dir: session_dir.clone(),
            memory_dir,
            worktrees_dir,
            turn_events: Arc::new(Mutex::new(VecDeque::new())),
            turn_in_flight: Arc::new(Mutex::new(false)),
            abort_flag: Arc::new(std::sync::atomic::AtomicBool::new(false)),
            dir_cache: Arc::new(RwLock::new(dir_cache)),
            edit_log: EditLog::new(&session_dir),
            session_runtime: Some(SessionRuntime::new(session_dir.clone())),
            workflow_engine: WorkflowEngine::new(),
            mcp_manager: McpManager::new(),
            lsp_provision_msgs: Arc::new(Mutex::new(VecDeque::new())),
            lsp_manager: Arc::new(Mutex::new(LspManager::new())),
            sessions: Vec::new(),
            transcript_cache: TranscriptCache::new(200),
            scroll: ScrollState::new(),
            input: InputState::new(),
            misc: MiscState::new(),
            dirty: true,
            quit: false,
        };

        // Load project-specific history
        let base_dir = state.memory_dir.parent().unwrap_or(&state.memory_dir);
        if let Some(root) = state.workspace_roots.first() {
            if let Ok(abs_root) = std::fs::canonicalize(root) {
                use sha2::Digest;
                let mut hasher = sha2::Sha256::new();
                hasher.update(abs_root.to_string_lossy().as_bytes());
                let hash_hex = format!("{:x}", hasher.finalize());
                let folder_name = abs_root.file_name()
                    .map(|n| n.to_string_lossy().to_string())
                    .unwrap_or_else(|| "root".to_string());
                let history_filename = format!("{}-{}.txt", folder_name, &hash_hex[..8]);
                let history_dir = base_dir.join("history");
                let _ = std::fs::create_dir_all(&history_dir);
                let history_file = history_dir.join(history_filename);

                if let Ok(content) = std::fs::read_to_string(&history_file) {
                    let history: Vec<String> = content
                        .lines()
                        .map(|s| s.to_string())
                        .filter(|s| !s.is_empty())
                        .collect();
                    state.input.history = history;
                }
                state.input.history_file = Some(history_file);
            }
        }

        // Fire-and-forget background LSP provisioning.
        //
        // Flow: spawn OS thread -> provision_all() probes/installs every
        // supported language server -> auto_connect() attaches whichever
        // ones ended up available to the shared `lsp_manager` -> log a line
        // per connected server and per failure.
        //
        // Why a raw thread and not a tokio task: this runs before the async
        // runtime's executor may be fully set up for this state, and the
        // provisioning work (shelling out to package managers, network
        // downloads) is blocking I/O; a dedicated thread keeps it off any
        // async executor entirely. It is deliberately not joined -- startup
        // must not block on language server installation, and failures are
        // logged rather than surfaced, since editing still works without LSP.
        if state.settings.lsp_auto_provision {
            let lsp_mgr = state.lsp_manager.clone();
            let msg_queue = state.lsp_provision_msgs.clone();
            std::thread::spawn(move || {
                use crate::app::lsp::provisioner::{self, ProvisionResult};

                fn push_msg(q: &Arc<Mutex<VecDeque<String>>>, msg: &str) {
                    if let Ok(mut q) = q.lock() {
                        q.push_back(msg.to_string());
                    }
                }

                // Wrap the msg_queue in a static-lifetime closure for use as ProgressFn.
                let progress: provisioner::ProgressFn = Some(&|msg: &str| push_msg(&msg_queue, msg));

                let report = |msg: &str| { if let Some(f) = &progress { f(msg); }};

                report("LSP: provisioning servers...");
                let results = provisioner::provision_all_with_progress(progress);
                report("LSP: connecting servers...");
                let connected = provisioner::auto_connect(&lsp_mgr, &results);
                for name in &connected {
                    tracing::info!("LSP: {} connected", name);
                    let m = format!("LSP: {} connected ✓", name); push_msg(&msg_queue, &m);
                }
                for r in &results {
                    if let ProvisionResult::Failed { language, server_name, reason, .. } = r {
                        tracing::warn!("LSP {} ({}): {}", server_name, language, reason);
                        let m = format!("LSP: {} ({}) ✗ - {}", server_name, language, reason); push_msg(&msg_queue, &m);
                    }
                }
                if connected.is_empty() {
                    let m = "LSP: no servers available — install manually or check prerequisites".to_string(); push_msg(&msg_queue, &m);
                } else {
                    let m = format!("LSP: {} server(s) connected", connected.len()); push_msg(&msg_queue, &m);
                }
            });
        }

        state
    }

    /// Whether an agent turn is currently running.
    ///
    /// Return: `false` (and logs a warning) if the mutex is poisoned, rather
    /// than propagating a panic.
    pub fn turn_in_flight(&self) -> bool {
        self.turn_in_flight.lock().map(|g| *g).unwrap_or_else(|_| {
            tracing::warn!("[state] turn_in_flight mutex poisoned");
            false
        })
    }

    /// Shut down every running LSP server process.
    ///
    /// Why: called on app exit so language servers don't linger as orphaned
    /// processes; silently no-ops if the mutex is poisoned since there is
    /// nothing more useful to do at shutdown time.
    pub fn shutdown_lsp(&mut self) {
        if let Ok(mut mgr) = self.lsp_manager.lock() {
            mgr.shutdown_all();
        }
    }

    /// Append a message to the transcript, evicting the oldest entry once
    /// `max_lines` is exceeded, and mark both the cache and the app dirty.
    pub fn push_transcript(&mut self, msg: ChatMessageDisplay) {
        self.transcript_cache.messages.push(msg);
        if self.transcript_cache.messages.len() > self.transcript_cache.max_lines {
            self.transcript_cache.messages.remove(0);
        }
        self.transcript_cache.dirty = true;
        self.dirty = true;
    }

    /// Queue a toast notification for display and mark the app dirty.
    pub fn push_toast(&mut self, toast: Toast) {
        self.misc.push_toast(toast);
        self.dirty = true;
    }

    /// Resolve the base directory that stores this session (grandparent of
    /// `session_dir`, i.e. the sessions root, not the individual session
    /// folder).
    ///
    /// Why: falls back progressively -- grandparent, then parent, then
    /// `session_dir` itself -- logging a warning at each step down, so this
    /// never fails even on a shallow path.
    pub fn store_base_dir(&self) -> std::path::PathBuf {
        self.session_dir.parent()
            .and_then(|p| p.parent())
            .map(|p| p.to_path_buf())
            .unwrap_or_else(|| {
                tracing::warn!("[state] session_dir '{}' has no grandparent, using parent", self.session_dir.display());
                self.session_dir.parent()
                    .map(|p| p.to_path_buf())
                    .unwrap_or_else(|| {
                        tracing::warn!("[state] session_dir '{}' has no parent at all, using itself", self.session_dir.display());
                        self.session_dir.clone()
                    })
            })
    }

    /// Build a `ToolCtx` for tool calls originating from the main agent.
    pub fn tool_ctx(&self) -> crate::tool::ToolCtx {
        self.tool_ctx_for(Origin::Main)
    }

    /// Build a `ToolCtx` scoped to the given call origin (main, subagent,
    /// reviewer), copying workspace/session/memory paths from state.
    pub fn tool_ctx_for(&self, origin: Origin) -> crate::tool::ToolCtx {
        crate::tool::ToolCtx {
            workspaces: self.workspace_roots.clone(),
            session_dir: self.session_dir.clone(),
            memory_dir: self.memory_dir.clone(),
            worktrees_dir: self.worktrees_dir.clone(),
            dir_cache: self.dir_cache.clone(),
            origin,
            graduated_checks: Vec::new(),
            lsp_manager: self.lsp_manager.clone(),
            turn_events: Some(self.turn_events.clone()),
            workflow_findings: None,
        }
    }
}