//! Classroom generation commands
//!
//! - `classroom_generate` — start 4-stage pipeline, emit progress events
//! - `classroom_generation_progress` — query current progress
//! - `classroom_cancel_generation` — cancel active generation
//! - `classroom_get` — retrieve generated classroom data
//! - `classroom_list` — list all generated classrooms

use serde::{Deserialize, Serialize};
use tauri::{AppHandle, Emitter, State};

use zclaw_kernel::generation::{
    Classroom, GenerationPipeline, GenerationRequest as KernelGenRequest, GenerationStage,
    TeachingStyle, DifficultyLevel,
};

use super::{ClassroomStore, GenerationTasks};
use crate::kernel_commands::KernelState;

// ---------------------------------------------------------------------------
// Request / Response types
// ---------------------------------------------------------------------------

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ClassroomGenerateRequest {
    pub topic: String,
    pub document: Option<String>,
    pub style: Option<String>,
    pub level: Option<String>,
    pub target_duration_minutes: Option<u32>,
    pub scene_count: Option<usize>,
    pub custom_instructions: Option<String>,
    pub language: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ClassroomGenerateResponse {
    pub classroom_id: String,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ClassroomProgressResponse {
    pub stage: String,
    pub progress: u8,
    pub activity: String,
    pub items_progress: Option<(usize, usize)>,
}

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

fn parse_style(s: Option<&str>) -> TeachingStyle {
    match s.unwrap_or("lecture") {
        "discussion" => TeachingStyle::Discussion,
        "pbl" => TeachingStyle::Pbl,
        "flipped" => TeachingStyle::Flipped,
        "socratic" => TeachingStyle::Socratic,
        _ => TeachingStyle::Lecture,
    }
}

fn parse_level(l: Option<&str>) -> DifficultyLevel {
    match l.unwrap_or("intermediate") {
        "beginner" => DifficultyLevel::Beginner,
        "advanced" => DifficultyLevel::Advanced,
        "expert" => DifficultyLevel::Expert,
        _ => DifficultyLevel::Intermediate,
    }
}

fn stage_name(stage: &GenerationStage) -> &'static str {
    match stage {
        GenerationStage::AgentProfiles => "agent_profiles",
        GenerationStage::Outline => "outline",
        GenerationStage::Scene => "scene",
        GenerationStage::Complete => "complete",
    }
}

// ---------------------------------------------------------------------------
// Commands
// ---------------------------------------------------------------------------

/// Start classroom generation (4-stage pipeline).
/// Progress events are emitted via `classroom:progress`.
/// Supports cancellation between stages by removing the task from GenerationTasks.
// @reserved: classroom generation
// @connected
#[tauri::command]
pub async fn classroom_generate(
    app: AppHandle,
    store: State<'_, ClassroomStore>,
    tasks: State<'_, GenerationTasks>,
    kernel_state: State<'_, KernelState>,
    persistence: State<'_, crate::classroom_commands::persist::ClassroomPersistence>,
    request: ClassroomGenerateRequest,
) -> Result<ClassroomGenerateResponse, String> {
    if request.topic.trim().is_empty() {
        return Err("Topic is required".to_string());
    }

    let topic_clone = request.topic.clone();

    let kernel_request = KernelGenRequest {
        topic: request.topic.clone(),
        document: request.document.clone(),
        style: parse_style(request.style.as_deref()),
        level: parse_level(request.level.as_deref()),
        target_duration_minutes: request.target_duration_minutes.unwrap_or(30),
        scene_count: request.scene_count,
        custom_instructions: request.custom_instructions.clone(),
        language: request.language.clone().or_else(|| Some("zh-CN".to_string())),
    };

    // Register generation task so cancellation can check it
    {
        use zclaw_kernel::generation::GenerationProgress;
        let mut t = tasks.lock().await;
        t.insert(topic_clone.clone(), GenerationProgress {
            stage: zclaw_kernel::generation::GenerationStage::AgentProfiles,
            progress: 0,
            activity: "Starting generation...".to_string(),
            items_progress: None,
            eta_seconds: None,
        });
    }

    // Get LLM driver from kernel if available, otherwise use placeholder mode
    let (pipeline, has_driver) = {
        let ks = kernel_state.lock().await;
        if let Some(kernel) = ks.as_ref() {
            (GenerationPipeline::with_driver(kernel.driver(), kernel.config().model().to_string()), true)
        } else {
            (GenerationPipeline::new(), false)
        }
    };

    // Helper: check if cancelled (try_lock avoids blocking the async runtime)
    let is_cancelled = || {
        match tasks.try_lock() {
            Ok(t) => !t.contains_key(&topic_clone),
            Err(_) => false, // Lock contested — treat as not cancelled
        }
    };

    // Helper: emit progress event
    let emit_progress = |stage: &str, progress: u8, activity: &str| {
        let _ = app.emit("classroom:progress", serde_json::json!({
            "topic": &topic_clone,
            "stage": stage,
            "progress": progress,
            "activity": activity
        }));
    };

    // ── Stage 0: Agent Profiles ──
    emit_progress("agent_profiles", 5, "生成课堂角色...");
    let agents = pipeline.generate_agent_profiles(&kernel_request).await;
    emit_progress("agent_profiles", 25, "角色生成完成");
    if is_cancelled() {
        return Err("Generation cancelled".to_string());
    }

    // ── Stage 1: Outline ──
    emit_progress("outline", 30, "分析主题，生成大纲...");
    let outline = pipeline.generate_outline(&kernel_request).await
        .map_err(|e| format!("Outline generation failed: {}", e))?;
    emit_progress("outline", 50, &format!("大纲完成：{} 个场景", outline.len()));
    if is_cancelled() {
        return Err("Generation cancelled".to_string());
    }

    // ── Stage 2: Scenes (parallel) ──
    emit_progress("scene", 55, &format!("并行生成 {} 个场景...", outline.len()));
    let scenes = pipeline.generate_scenes(&outline).await
        .map_err(|e| format!("Scene generation failed: {}", e))?;
    if is_cancelled() {
        return Err("Generation cancelled".to_string());
    }

    // ── Stage 3: Assemble ──
    emit_progress("complete", 90, "组装课堂...");

    // Build classroom directly (pipeline.build_classroom is private)
    let total_duration: u32 = scenes.iter().map(|s| s.content.duration_seconds).sum();
    let objectives = outline.iter()
        .take(3)
        .map(|item| format!("理解: {}", item.title))
        .collect::<Vec<_>>();
    let classroom_id = uuid::Uuid::new_v4().to_string();

    let classroom = Classroom {
        id: classroom_id.clone(),
        title: format!("课堂: {}", kernel_request.topic),
        description: format!("{:?} 风格课堂 — {}", kernel_request.style, kernel_request.topic),
        topic: kernel_request.topic.clone(),
        style: kernel_request.style,
        level: kernel_request.level,
        total_duration,
        objectives,
        scenes,
        agents,
        metadata: zclaw_kernel::generation::ClassroomMetadata {
            generated_at: std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .unwrap()
                .as_millis() as i64,
            source_document: kernel_request.document.map(|_| "user_document".to_string()),
            model: None,
            version: "2.0.0".to_string(),
            is_placeholder: !has_driver, // P2-10: true when no LLM driver available
            custom: serde_json::Map::new(),
        },
    };

    // Store classroom
    {
        let mut s = store.lock().await;
        s.insert(classroom_id.clone(), classroom.clone());
        // Persist to SQLite
        if let Err(e) = persistence.save_classroom(&classroom).await {
            tracing::warn!("[ClassroomGenerate] Failed to persist classroom {}: {}", classroom_id, e);
        }
    }

    // Clear generation task
    {
        let mut t = tasks.lock().await;
        t.remove(&topic_clone);
    }

    // Emit completion
    emit_progress("complete", 100, "课堂生成完成");

    Ok(ClassroomGenerateResponse {
        classroom_id,
    })
}

/// @reserved — no frontend UI yet
/// Get current generation progress for a topic
#[tauri::command]
pub async fn classroom_generation_progress(
    tasks: State<'_, GenerationTasks>,
    topic: String,
) -> Result<ClassroomProgressResponse, String> {
    let t = tasks.lock().await;
    let progress = t.get(&topic);
    Ok(ClassroomProgressResponse {
        stage: progress.map(|p| stage_name(&p.stage).to_string()).unwrap_or_else(|| "none".to_string()),
        progress: progress.map(|p| p.progress).unwrap_or(0),
        activity: progress.map(|p| p.activity.clone()).unwrap_or_default(),
        items_progress: progress.and_then(|p| p.items_progress),
    })
}

/// Cancel an active generation
// @connected
#[tauri::command]
pub async fn classroom_cancel_generation(
    tasks: State<'_, GenerationTasks>,
    topic: String,
) -> Result<(), String> {
    let mut t = tasks.lock().await;
    t.remove(&topic);
    Ok(())
}

/// Retrieve a generated classroom by ID
// @reserved: classroom generation
// @connected
#[tauri::command]
pub async fn classroom_get(
    store: State<'_, ClassroomStore>,
    classroom_id: String,
) -> Result<Classroom, String> {
    let s = store.lock().await;
    s.get(&classroom_id)
        .cloned()
        .ok_or_else(|| format!("Classroom '{}' not found", classroom_id))
}

/// @reserved — no frontend UI yet
/// List all generated classrooms (id + title only)
#[tauri::command]
pub async fn classroom_list(
    store: State<'_, ClassroomStore>,
) -> Result<Vec<serde_json::Value>, String> {
    let s = store.lock().await;
    Ok(s.values().map(|c| serde_json::json!({
        "id": c.id,
        "title": c.title,
        "topic": c.topic,
        "totalDuration": c.total_duration,
        "sceneCount": c.scenes.len(),
    })).collect())
}