use std::collections::VecDeque;

use crate::app::harness::Verdict;
use sha2::Digest;
use crate::app::mode::ModeKind;
use crate::app::review::{should_trigger_review, trigger_review};
use crate::app::state::rest::{AppStateRest, ChatMessageDisplay};
use crate::app::state::runtime::TurnEvent;
use crate::app::state::types::{AgentMode, Origin, Overlay, Toast, ToastKind};
use crate::dto::chat::message::{ChatMessage, Role};

const MAX_AGENT_STEPS: usize = 40;

#[derive(Debug, Clone)]
pub enum Action {
    Quit,
    ForceQuit,
    SwitchMode(ModeKind),
    SubmitInput(String),
    InsertChar(char),
    DeleteChar,
    DeleteCharRight,
    CursorLeft,
    CursorRight,
    HistoryUp,
    HistoryDown,
    ScrollUp,
    ScrollDown,
    OpenOverlay(Overlay),
    CloseOverlay,
    ToggleYoloArm,
    CycleAgentMode,
    ToolResult {
        tool_call_id: String,
        output: String,
        is_error: bool,
    },
    StreamToken(String),
    StreamDone,
    StreamError(String),
    SystemNote {
        kind: String,
        message: String,
    },
    RunCommand(String),
    QuitConfirm,
    Resize(u16, u16),
    Tick,
    LessonExport {
        path: String,
    },
    LessonImport {
        path: String,
    },
    LessonAccept {
        name: String,
    },
    LessonReject {
        name: String,
    },
    SaveSession,
    ResumeSession,
    RefreshSessions,
}

pub fn apply_action(state: &mut AppStateRest, action: Action) {
    match action {
        Action::Quit => {
            save_current_session(state);
            auto_create_retrospective(state);
            state.quit = true;
        }
        Action::ForceQuit => {
            save_current_session(state);
            state.quit = true;
        }
        Action::SwitchMode(mode) => {
            state.misc.overlay = match mode {
                ModeKind::Chat
                | ModeKind::Agents
                | ModeKind::Bash
                | ModeKind::Workflow => Overlay::None,
                ModeKind::Help => Overlay::Help,
                ModeKind::Settings => Overlay::Settings,
                ModeKind::SessionHub => Overlay::SessionHub,
                ModeKind::QuitConfirm => Overlay::QuitConfirm,
                ModeKind::Onboard => Overlay::Onboard,
                ModeKind::OnboardProvider => Overlay::OnboardProvider,
                ModeKind::Picker => Overlay::Picker,
                ModeKind::KeyInput => Overlay::KeyInput,
                ModeKind::Editor => Overlay::Editor,
                ModeKind::Effort => Overlay::Effort,
                ModeKind::Mcp => Overlay::Mcp,
                ModeKind::Security => Overlay::Security,
                ModeKind::Todo => Overlay::Todo,
                ModeKind::Rewind => Overlay::Rewind,
                ModeKind::Loading => Overlay::Loading,
            };
            state.dirty = true;
        }
        Action::SubmitInput(text) => {
            state.input.submit();
            let text = text.trim().to_string();
            if text.is_empty() {
                state.dirty = true;
                return;
            }
            state.push_transcript(ChatMessageDisplay::new(Role::User, text.clone()));
            if let Some(ref mut rt) = state.session_runtime {
                rt.push_message(ChatMessage::user(text));
            }
            spawn_turn(state);
            state.dirty = true;
        }
        Action::InsertChar(c) => {
            state.input.insert(c);
            state.dirty = true;
        }
        Action::DeleteChar => {
            state.input.delete_left();
            state.dirty = true;
        }
        Action::DeleteCharRight => {
            state.input.delete_right();
            state.dirty = true;
        }
        Action::CursorLeft => {
            state.input.char_left();
        }
        Action::CursorRight => {
            state.input.char_right();
        }
        Action::HistoryUp => {
            state.input.history_up();
            state.dirty = true;
        }
        Action::HistoryDown => {
            state.input.history_down();
            state.dirty = true;
        }
        Action::ScrollUp => {
            let total = state.transcript_cache.messages.len();
            state.scroll.scroll_up();
            state.scroll.scroll_down(total);
            state.dirty = true;
        }
        Action::ScrollDown => {
            let total = state.transcript_cache.messages.len();
            state.scroll.scroll_down(total);
            state.dirty = true;
        }
        Action::OpenOverlay(overlay) => {
            state.misc.overlay = overlay;
            state.dirty = true;
        }
        Action::CloseOverlay => {
            state.misc.overlay = Overlay::None;
            state.dirty = true;
        }
        Action::ToggleYoloArm => {
            state.misc.yolo_armed = !state.misc.yolo_armed;
            state.dirty = true;
        }
        Action::CycleAgentMode => {
            let next = state.mode.cycle();
            state.set_mode(next);
            let toast = Toast::new(ToastKind::Info, format!("Mode: {}", state.mode.name()));
            state.push_toast(toast);
            state.dirty = true;
        }
        Action::ToolResult {
            tool_call_id,
            output,
            is_error,
        } => {
            if let Some(ref mut rt) = state.session_runtime {
                rt.push_message(ChatMessage::tool_result(tool_call_id.clone(), output.clone()));
                rt.tool_call_results.push(
                    crate::app::state::runtime::ToolCallResult {
                        tool_call_id,
                        tool_name: String::new(),
                        output,
                        is_error,
                        duration_ms: 0,
                    },
                );
            }
            state.dirty = true;
        }
        Action::StreamToken(token) => {
            if let Some(ref mut rt) = state.session_runtime {
                let found = rt.messages.iter_mut().rev().find(|m| {
                    matches!(m.role, crate::dto::chat::message::Role::Assistant)
                });
                if let Some(last) = found {
                    let current = last.content.take().unwrap_or_default();
                    last.content = Some(current + &token);
                } else {
                    let mut msg = ChatMessage::assistant(None);
                    msg.content = Some(token);
                    rt.push_message(msg);
                }
            }
            state.dirty = true;
        }
        Action::StreamDone => {
            state.dirty = true;
        }
        Action::StreamError(msg) => {
            let toast = crate::app::state::types::Toast::new(
                crate::app::state::types::ToastKind::Error,
                msg,
            );
            state.push_toast(toast);
        }
        Action::SystemNote { kind: _kind, message } => {
            let toast = crate::app::state::types::Toast::new(
                crate::app::state::types::ToastKind::Info,
                message,
            );
            state.push_toast(toast);
        }
        Action::RunCommand(text) => {
            if let Some(ref mut rt) = state.session_runtime {
                rt.push_message(ChatMessage::user(text));
            }
            state.dirty = true;
        }
        Action::QuitConfirm => {
            state.misc.overlay = Overlay::QuitConfirm;
            state.dirty = true;
        }
        Action::Resize(w, _h) => {
            state.scroll.set_max_visible(w as usize);
            state.dirty = true;
        }
        Action::LessonExport { path } => {
            let dest = std::path::Path::new(&path);
            if let Some(parent) = dest.parent() {
                let _ = std::fs::create_dir_all(parent);
            }
            match crate::model::memory::export_lessons(&state.memory_dir, dest) {
                Ok(_) => {
                    state.push_toast(crate::app::state::types::Toast::new(
                        crate::app::state::types::ToastKind::Success,
                        format!("lessons exported to {}", path),
                    ));
                }
                Err(e) => {
                    state.push_toast(crate::app::state::types::Toast::new(
                        crate::app::state::types::ToastKind::Error,
                        format!("export failed: {}", e),
                    ));
                }
            }
            state.dirty = true;
        }
        Action::LessonImport { path } => {
            let src = std::path::Path::new(&path);
            match crate::model::memory::import_lessons(&state.memory_dir, src) {
                Ok(count) => {
                    state.push_toast(crate::app::state::types::Toast::new(
                        crate::app::state::types::ToastKind::Success,
                        format!("imported {} lessons from {}", count, path),
                    ));
                }
                Err(e) => {
                    state.push_toast(crate::app::state::types::Toast::new(
                        crate::app::state::types::ToastKind::Error,
                        format!("import failed: {}", e),
                    ));
                }
            }
            state.dirty = true;
        }
        Action::SaveSession => {
            save_current_session(state);
            state.push_toast(Toast::new(ToastKind::Success, "session saved".to_string()));
            state.dirty = true;
        }
        Action::ResumeSession => {
            let base = state.store_base_dir();
            let sessions = crate::model::session::Session::list(&base);
            let target = sessions.into_iter()
                .filter(|s| s.id != state.session_id)
                .max_by_key(|s| s.updated_at);
            if let Some(session) = target {
                let conv_path = session.conversation_path(&base);
                let loaded_msgs: Vec<crate::dto::chat::message::ChatMessage> =
                    std::fs::read_to_string(&conv_path)
                        .ok()
                        .and_then(|data| serde_json::from_str(&data).ok())
                        .unwrap_or_default();
                state.session_id = session.id.clone();
                state.session_dir = session.session_dir(&base);
                state.session_runtime = Some(crate::app::state::runtime::SessionRuntime::new(
                    state.session_dir.clone(),
                ));
                state.transcript_cache.messages.clear();
                if let Some(ref mut rt) = state.session_runtime {
                    for msg in loaded_msgs {
                        let display = ChatMessageDisplay::new(
                            msg.role.clone(),
                            msg.content.clone().unwrap_or_default(),
                        );
                        state.transcript_cache.messages.push(display);
                        rt.push_message(msg);
                    }
                }
                state.push_toast(Toast::new(ToastKind::Success,
                    format!("resumed session: {}", session.title)));
            } else {
                state.push_toast(Toast::new(ToastKind::Info,
                    "no other sessions to resume".to_string()));
            }
            state.dirty = true;
        }
        Action::RefreshSessions => {
            let base = state.store_base_dir();
            state.sessions = crate::model::session::Session::list(&base);
            state.dirty = true;
        }
        Action::Tick => {
            let now_ms = chrono::Utc::now().timestamp_millis();
            state.misc.drain_expired_toasts(now_ms);
    crate::app::review::maybe_run_staleness_sweep(state);
    if let Some(ref rt) = state.session_runtime {
        let _ = crate::app::review::process_pending_lessons(&rt.session_dir, &state.memory_dir);
    }

    let events: Vec<TurnEvent> = {
                if let Ok(mut q) = state.turn_events.lock() {
                    q.drain(..).collect()
                } else {
                    Vec::new()
                }
            };
            let mut turn_finished = false;
            for event in events {
                match event {
                    TurnEvent::AssistantMessage(msg) => {
                        let display_content = msg.content.clone().unwrap_or_default();
                        if !display_content.is_empty() {
                            state.push_transcript(ChatMessageDisplay::new(Role::Assistant, display_content));
                        }
                        if let Some(ref mut rt) = state.session_runtime {
                            rt.push_message(msg);
                        }
                    }
                    TurnEvent::ToolResult { tool_call_id, tool_name, output, is_error } => {
                        state.push_transcript(ChatMessageDisplay::new(
                            Role::Tool,
                            format!("{}: {}", tool_name, output),
                        ));
                        if let Some(ref mut rt) = state.session_runtime {
                            rt.push_message(ChatMessage::tool_result(tool_call_id.clone(), output.clone()));
                            rt.tool_call_results.push(crate::app::state::runtime::ToolCallResult {
                                tool_call_id,
                                tool_name,
                                output,
                                is_error,
                                duration_ms: 0,
                            });
                        }
                    }
                    TurnEvent::SystemNote { kind, message } => {
                        if kind == "edits" {
                            if let Some(ref mut rt) = state.session_runtime {
                                if let Ok(count) = message.parse::<u32>() {
                                    rt.edit_count += count;
                                }
                            }
                            if should_trigger_review(state, Origin::Main) {
                                let _ = trigger_review(state);
                            }
                        } else if kind == "review" {
                            let lessons_found = if message.contains("lesson") || message.contains("Lesson") {
                                message.rsplit(' ').next().and_then(|w| {
                                    w.trim_end_matches(')').trim_end_matches('s')
                                     .split('(').next_back()
                                     .and_then(|n| n.parse::<u32>().ok())
                                }).unwrap_or(0)
                            } else {
                                0
                            };
                            if let Some(ref mut rt) = state.session_runtime {
                                if lessons_found > 0 {
                                    rt.consecutive_empty_reviews = 0;
                                    rt.lesson_count += lessons_found;
                                } else {
                                    rt.consecutive_empty_reviews += 1;
                                }
                            }
                            state.push_toast(Toast::new(ToastKind::Info, message));
                        } else {
                            state.push_toast(Toast::new(ToastKind::Info, message));
                        }
                    }
                    TurnEvent::Error(msg) => {
                        let long_toast = Toast {
                            kind: ToastKind::Error,
                            message: msg.clone(),
                            created_at: chrono::Utc::now().timestamp_millis(),
                            lifetime_ms: 15000,
                        };
                        state.push_toast(long_toast);
                        state.push_transcript(ChatMessageDisplay::new(
                            crate::dto::chat::message::Role::System,
                            format!("Error: {}", msg),
                        ));
                        turn_finished = true;
                    }
                    TurnEvent::Done => {
                        turn_finished = true;
                    }
                }
            }
            if turn_finished {
                maybe_trigger_review(state);
            }
            if turn_finished || state.dirty {
                state.dirty = true;
            }
        }
        Action::LessonAccept { name } => {
            if let Some(ref rt) = state.session_runtime {
                let _ = crate::app::review::resolve_pending_lesson(
                    &rt.session_dir, &state.memory_dir, &name, true,
                );
            }
            state.push_toast(Toast::new(ToastKind::Success,
                format!("accepted lesson: {}", name)));
            state.dirty = true;
        }
        Action::LessonReject { name } => {
            if let Some(ref rt) = state.session_runtime {
                let _ = crate::app::review::resolve_pending_lesson(
                    &rt.session_dir, &state.memory_dir, &name, false,
                );
            }
            state.push_toast(Toast::new(ToastKind::Info,
                format!("rejected lesson: {}", name)));
            state.dirty = true;
        }
    }
}

fn spawn_turn(state: &AppStateRest) {
    let in_flight = if let Ok(guard) = state.turn_in_flight.lock() {
        *guard
    } else {
        return;
    };
    if in_flight {
        return;
    }
    let messages = state
        .session_runtime
        .as_ref()
        .map(|rt| rt.messages.clone())
        .unwrap_or_default();
    if messages.is_empty() {
        return;
    }
    let api_key = state.settings.api_key.clone().unwrap_or_default();
    let model = state.settings.model.clone();
    let mut tools = crate::tool::all_tools();
    tools.extend(state.mcp_manager.as_tools());
    let tool_defs = crate::tool::tool_defs(&tools);
    let ctx = state.tool_ctx();
    let mode = state.mode;
    let edit_session_dir = state.session_dir.clone();
    let session_id = state.session_id.clone();
    let turn_events = state.turn_events.clone();
    let in_flight_flag = state.turn_in_flight.clone();
    let workspace_roots: Vec<std::path::PathBuf> = ctx.workspaces.clone();

    *in_flight_flag.lock().unwrap() = true;

    let events_q = turn_events.clone();

    std::thread::spawn(move || {
        let tc = TurnCtx {
            client: crate::service::provider::LlmClient::new(api_key, model),
            tdefs: tool_defs,
            tools,
            ctx,
            mode,
            workspace_roots,
            edit_log_session_dir: edit_session_dir,
            session_id,
        };
        let result = run_agent_turn(tc, &messages, &events_q);
        if let Err(e) = result {
            if let Ok(mut q) = events_q.lock() {
                q.push_back(TurnEvent::Error(e.to_string()));
            }
        }
        if let Ok(mut flag) = in_flight_flag.lock() {
            *flag = false;
        }
    });
}

struct TurnCtx {
    client: crate::service::provider::LlmClient,
    tdefs: Vec<crate::dto::provider::request::ToolDef>,
    tools: Vec<Box<dyn crate::tool::Tool>>,
    ctx: crate::tool::ToolCtx,
    mode: AgentMode,
    workspace_roots: Vec<std::path::PathBuf>,
    edit_log_session_dir: std::path::PathBuf,
    session_id: String,
}

fn run_agent_turn(
    tc: TurnCtx,
    messages: &[ChatMessage],
    events_q: &std::sync::Mutex<VecDeque<TurnEvent>>,
) -> anyhow::Result<()> {
    let mut msgs = messages.to_vec();
    let mut edits_this_turn = 0u32;

    let system_text = format!(
        "{}\n\n{}",
        crate::resources::SYSTEM_PROMPT,
        crate::resources::SYSTEM_TOOLS,
    );
    if !msgs.iter().any(|m| matches!(m.role, crate::dto::chat::message::Role::System)) {
        msgs.insert(0, ChatMessage::system(system_text));
    }

    for _step in 0..MAX_AGENT_STEPS {
        let response = tc
            .client
            .chat_with_tools(&msgs, Some(tc.tdefs.clone()))?;

        let has_tool_calls = response.tool_calls.is_some()
            && response.tool_calls.as_ref().is_some_and(|tc| !tc.is_empty());

        let content = response.content.clone().unwrap_or_default();
        if has_tool_calls {
            let tool_calls = response.tool_calls.clone().unwrap_or_default();
            msgs.push(response);
            for tool_call in tool_calls {
                let tool_name = tool_call.function.name.clone();
                let args = crate::dto::chat::tool::sanitize_tool_arguments(
                    &tool_call.function.arguments,
                );

                let ws_roots: Vec<&std::path::Path> =
                    tc.workspace_roots.iter().map(|p| p.as_path()).collect();
                let verdict = crate::app::harness::Harness::gate_tool_call(
                    &tool_name,
                    &args,
                    &tc.mode,
                    &ws_roots,
                );

                let is_edit_tool = tool_name == "write" || tool_name == "edit";
                let (output, is_error, is_edit) = match verdict {
                    Verdict::Allow => match execute_one_tool(
                        &tc.tools,
                        &tc.ctx,
                        &tool_name,
                        &args,
                        &tc.edit_log_session_dir,
                        &tc.session_id,
                    ) {
                        Ok(result) => (result, false, is_edit_tool),
                        Err(e) => (e.to_string(), true, false),
                    },
                    Verdict::Block(reason) => (format!("Blocked: {}", reason), true, false),
                    Verdict::Escalate => (
                        "Tool requires approval. Switch to Auto mode or provide explicit approval."
                            .to_string(),
                        true,
                        false,
                    ),
                };

                if is_edit {
                    edits_this_turn += 1;
                }

                {
                    if let Ok(mut q) = events_q.lock() {
                        q.push_back(TurnEvent::ToolResult {
                            tool_call_id: tool_call.id.clone(),
                            tool_name: tool_name.clone(),
                            output: output.clone(),
                            is_error,
                        });
                    }
                }

                let tool_msg = ChatMessage::tool_result(tool_call.id.clone(), output);
                msgs.push(tool_msg);
            }
        } else {
            if !content.is_empty() {
                if let Ok(mut q) = events_q.lock() {
                    q.push_back(TurnEvent::AssistantMessage(response));
                }
            }
            break;
        }
    }

    if edits_this_turn > 0 {
        if let Ok(mut q) = events_q.lock() {
            q.push_back(TurnEvent::SystemNote {
                kind: "edits".to_string(),
                message: edits_this_turn.to_string(),
            });
        }
    }

    if let Ok(mut q) = events_q.lock() {
        q.push_back(TurnEvent::Done);
    }

    Ok(())
}

fn execute_one_tool(
    tools: &[Box<dyn crate::tool::Tool>],
    ctx: &crate::tool::ToolCtx,
    name: &str,
    args: &serde_json::Value,
    session_dir: &std::path::Path,
    session_id: &str,
) -> anyhow::Result<String> {
    for tool in tools {
        if tool.name() == name {
            let result = tool.run(ctx, args)?;
            if name == "write" || name == "edit" {
                let reason = args
                    .get("reason")
                    .and_then(|v| v.as_str())
                    .unwrap_or("unnamed");
                let path = args
                    .get("path")
                    .and_then(|v| v.as_str())
                    .unwrap_or("unknown");
                let content_sha256 = {
                    let content = args.get("content").or_else(|| args.get("new"));
                    let hash = sha2::Sha256::digest(
                        content.and_then(|v| v.as_str()).unwrap_or("").as_bytes(),
                    );
                    format!("{:x}", hash)
                };
                let bytes_delta = if name == "write" {
                    args.get("content")
                        .and_then(|v| v.as_str())
                        .map(|s| s.len() as i64)
                        .unwrap_or(0)
                } else {
                    let old = args.get("old").and_then(|v| v.as_str()).unwrap_or("");
                    let new = args.get("new").and_then(|v| v.as_str()).unwrap_or("");
                    (new.len() as i64 - old.len() as i64).abs()
                };
                let entry = crate::model::editlog::EditLogEntry {
                    ts: chrono::Utc::now().timestamp_millis(),
                    tool: name.to_string(),
                    path: path.to_string(),
                    reason: reason.to_string(),
                    content_sha256,
                    bytes_delta,
                    origin: ctx.origin.tag(),
                    session_id: session_id.to_string(),
                };
                let mut el = crate::model::editlog::EditLog::new(session_dir);
                el.append(entry).ok();
            }
            return Ok(result);
        }
    }
    anyhow::bail!("tool not found: {}", name)
}

fn maybe_trigger_review(state: &mut AppStateRest) {
    if !state.settings.review_enabled {
        return;
    }
    let edit_count = state
        .session_runtime
        .as_ref()
        .map(|rt| rt.edit_count)
        .unwrap_or(0);
    if edit_count == 0 {
        return;
    }
    state.push_toast(Toast::new(
        ToastKind::Info,
        format!("{} file(s) modified this turn. Review available.", edit_count),
    ));
}

fn save_current_session(state: &AppStateRest) {
    let base = state.store_base_dir();
    let session = crate::model::session::Session::new(
        state.session_id.clone(),
        "session".to_string(),
    );
    let _ = session.save(&base);
    if let Some(ref rt) = state.session_runtime {
        let conv_path = session.conversation_path(&base);
        if let Ok(data) = serde_json::to_string(&rt.messages) {
            let _ = std::fs::write(&conv_path, data);
        }
    }
}

fn auto_create_retrospective(state: &mut AppStateRest) {
    if state.session_runtime.is_none() {
        return;
    }
    let session = crate::model::session::Session::new(
        state.session_id.clone(),
        "session".to_string(),
    );
    match crate::model::memory::auto_create_retrospective(&state.session_dir, &session) {
        Ok(Some(retro)) => {
            state.push_toast(crate::app::state::types::Toast::new(
                crate::app::state::types::ToastKind::Info,
                format!("Retrospective created: {}", retro.name),
            ));
        }
        Ok(None) => {}
        Err(e) => {
            let _ = e;
        }
    }
    let lessons: Vec<crate::model::memory::Memory> = crate::model::memory::Memory::list(&state.memory_dir)
        .iter()
        .filter_map(|n| crate::model::memory::Memory::read(&state.memory_dir, n).ok())
        .filter(|m| m.kind == "lesson")
        .collect();
    if let Some(global_dir) = dirs::data_dir().map(|d| d.join("zesdex")) {
        for lesson in &lessons {
            if lesson.scope.as_deref() != Some("global") {
                let _ = crate::model::memory::promote_with_consensus(&global_dir, lesson);
            }
        }
    }
}