use axum::Json;
use axum::extract::{Extension, FromRef, State};
use erp_core::rbac::require_permission;
use erp_core::types::{ApiResponse, TenantContext};
use serde::{Deserialize, Serialize};

use crate::agent::orchestrator::AgentRunParams;
use crate::agent::tool::ToolContext;
use crate::agent::tools::QueryPatientVitalsTool;
use crate::agent::{AgentOrchestrator, ToolRegistry};
use crate::config_resolver;
use crate::dto::{ChatMessage, ChatMessageRole};
use crate::state::AiState;

// === 请求 / 响应 ===

#[derive(Debug, Deserialize, utoipa::ToSchema)]
pub struct ChatRequest {
    pub message: String,
    pub history: Option<Vec<ChatHistoryItem>>,
    /// 可选：关联患者 ID（从用户档案中获取）
    pub patient_id: Option<uuid::Uuid>,
}

#[derive(Debug, Deserialize, Serialize, utoipa::ToSchema)]
pub struct ChatHistoryItem {
    pub role: String,
    pub content: String,
}

#[derive(Debug, Serialize, utoipa::ToSchema)]
pub struct ChatResponse {
    pub reply: String,
    pub message_id: String,
    pub iterations: usize,
}

#[utoipa::path(
    post,
    path = "/ai/chat",
    request_body = ChatRequest,
    responses((status = 200, description = "AI Agent 回复")),
    tag = "AI 客服",
    security(("bearer_auth" = [])),
)]
pub async fn chat<S>(
    Extension(ctx): Extension<TenantContext>,
    State(state): State<S>,
    Json(body): Json<ChatRequest>,
) -> Result<Json<ApiResponse<ChatResponse>>, erp_core::error::AppError>
where
    AiState: FromRef<S>,
    S: Clone + Send + Sync + 'static,
{
    require_permission(&ctx, "ai.chat.send")?;

    let message = body.message.trim();
    if message.is_empty() {
        return Err(erp_core::error::AppError::Validation("消息不能为空".into()));
    }
    if message.len() > 2000 {
        return Err(erp_core::error::AppError::Validation(
            "消息长度不能超过 2000 字".into(),
        ));
    }

    let ai_state = AiState::from_ref(&state);

    // 从 settings 表加载 AI 配置（替代硬编码）
    let config = config_resolver::load_ai_config(ctx.tenant_id, &ai_state.db).await;

    // 构建 Agent 消息历史
    let mut messages = vec![];

    // 将前端传来的历史转换为 Agent ChatMessage
    if let Some(ref hist) = body.history {
        let filtered: Vec<&ChatHistoryItem> = hist
            .iter()
            .filter(|h| h.role == "user" || h.role == "assistant")
            .collect();
        let start = filtered.len().saturating_sub(10);
        for h in &filtered[start..] {
            messages.push(ChatMessage {
                role: if h.role == "user" {
                    ChatMessageRole::User
                } else {
                    ChatMessageRole::Assistant
                },
                content: h.content.clone(),
                tool_calls: None,
                tool_call_id: None,
            });
        }
    }

    // 添加当前用户消息
    messages.push(ChatMessage {
        role: ChatMessageRole::User,
        content: message.to_string(),
        tool_calls: None,
        tool_call_id: None,
    });

    // 解析 Provider — Agent 需要 Function Calling，精确获取 Claude/OpenAI
    let provider_arc = ai_state
        .provider_registry
        .get_provider("claude")
        .or_else(|| ai_state.provider_registry.get_provider("openai"))
        .ok_or_else(|| {
            tracing::error!("No FC-capable provider found (need claude or openai)");
            erp_core::error::AppError::Internal(
                "AI Agent 暂时不可用，需要 Claude 或 OpenAI 提供商".into(),
            )
        })?;

    // 构建 ToolRegistry — Phase 0 只有 query_patient_vitals
    let mut registry = ToolRegistry::new();
    registry.register(std::sync::Arc::new(QueryPatientVitalsTool));

    let tool_ctx = ToolContext {
        tenant_id: ctx.tenant_id,
        user_id: ctx.user_id,
        patient_id: body.patient_id,
        db: ai_state.db.clone(),
        health_provider: ai_state.health_provider.clone(),
    };

    let run_params = AgentRunParams {
        model: config.agent.model,
        temperature: config.agent.temperature,
        max_tokens: config.agent.max_tokens,
        max_iterations: config.agent.max_iterations,
    };

    tracing::info!(
        tenant_id = %ctx.tenant_id,
        user_id = %ctx.user_id,
        patient_id = ?body.patient_id,
        msg_len = message.len(),
        model = %run_params.model,
        temperature = run_params.temperature,
        max_tokens = run_params.max_tokens,
        max_iterations = run_params.max_iterations,
        "AI Agent chat request"
    );

    let provider_name = provider_arc.name().to_string();

    // 执行 Agent ReAct 循环
    let orchestrator = AgentOrchestrator::new(provider_arc, std::sync::Arc::new(registry));
    let result = orchestrator
        .run(
            &config.agent.system_prompt,
            &mut messages,
            &tool_ctx,
            &run_params,
        )
        .await
        .map_err(|e| {
            tracing::error!(error = %e, "AI Agent run failed");
            erp_core::error::AppError::Internal("AI 服务暂时不可用，请稍后再试".into())
        })?;

    let message_id = uuid::Uuid::now_v7().to_string();

    tracing::info!(
        tenant_id = %ctx.tenant_id,
        message_id = %message_id,
        iterations = result.iterations,
        input_tokens = result.total_input_tokens,
        output_tokens = result.total_output_tokens,
        "AI Agent response sent"
    );

    // 记录用量的 token 消耗
    if let Err(e) = ai_state
        .usage
        .log_usage(
            ctx.tenant_id,
            &provider_name,
            &run_params.model,
            "chat",
            result.total_input_tokens as u32,
            result.total_output_tokens as u32,
            0,
            0,
            false,
        )
        .await
    {
        tracing::warn!(error = %e, "Failed to log chat usage");
    }

    Ok(Json(ApiResponse::ok(ChatResponse {
        reply: result.reply,
        message_id,
        iterations: result.iterations,
    })))
}