//! Webhook 数据库服务层
//!
//! 提供 CRUD 操作和事件触发。

use sqlx::{FromRow, PgPool};
use crate::error::{SaasError, SaasResult};
use super::types::*;

// ─── 数据库行结构 ───────────────────────────────────────────────

#[derive(Debug, FromRow)]
#[allow(dead_code)]
struct WebhookSubscriptionRow {
    id: String,
    account_id: String,
    url: String,
    secret: String,
    events: Vec<String>,
    enabled: bool,
    created_at: String,
    updated_at: String,
}

impl WebhookSubscriptionRow {
    fn to_response(&self) -> WebhookSubscription {
        WebhookSubscription {
            id: self.id.clone(),
            account_id: self.account_id.clone(),
            url: self.url.clone(),
            events: self.events.clone(),
            enabled: self.enabled,
            created_at: self.created_at.clone(),
            updated_at: self.updated_at.clone(),
        }
    }
}

#[derive(Debug, FromRow)]
struct WebhookDeliveryRow {
    id: String,
    subscription_id: String,
    event: String,
    payload: serde_json::Value,
    response_status: Option<i32>,
    attempts: i32,
    delivered_at: Option<String>,
    created_at: String,
}

impl WebhookDeliveryRow {
    fn to_response(&self) -> WebhookDelivery {
        WebhookDelivery {
            id: self.id.clone(),
            subscription_id: self.subscription_id.clone(),
            event: self.event.clone(),
            payload: self.payload.clone(),
            response_status: self.response_status,
            attempts: self.attempts,
            delivered_at: self.delivered_at.clone(),
            created_at: self.created_at.clone(),
        }
    }
}

// ─── 内部查询行：触发 webhooks 时需要 secret 和 url ──────────

#[derive(Debug, FromRow)]
#[allow(dead_code)]
struct SubscriptionForDeliveryRow {
    id: String,
    url: String,
    secret: String,
}

// ─── CRUD 操作 ────────────────────────────────────────────────

/// 创建 Webhook 订阅
pub async fn create_subscription(
    db: &PgPool,
    account_id: &str,
    req: &CreateWebhookRequest,
) -> SaasResult<WebhookSubscription> {
    let id = uuid::Uuid::new_v4().to_string();
    let now = chrono::Utc::now().to_rfc3339();
    let secret = generate_secret();

    sqlx::query(
        "INSERT INTO webhook_subscriptions (id, account_id, url, secret, events, enabled, created_at, updated_at)
         VALUES ($1, $2, $3, $4, $5, true, $6, $6)"
    )
    .bind(&id)
    .bind(account_id)
    .bind(&req.url)
    .bind(&secret)
    .bind(&req.events)
    .bind(&now)
    .execute(db)
    .await?;

    Ok(WebhookSubscription {
        id,
        account_id: account_id.to_string(),
        url: req.url.clone(),
        events: req.events.clone(),
        enabled: true,
        created_at: now.clone(),
        updated_at: now,
    })
}

/// 列出账户的 Webhook 订阅
pub async fn list_subscriptions(
    db: &PgPool,
    account_id: &str,
) -> SaasResult<Vec<WebhookSubscription>> {
    let rows: Vec<WebhookSubscriptionRow> = sqlx::query_as(
        "SELECT id, account_id, url, secret, events, enabled, created_at, updated_at
         FROM webhook_subscriptions WHERE account_id = $1 ORDER BY created_at DESC"
    )
    .bind(account_id)
    .fetch_all(db)
    .await?;

    Ok(rows.iter().map(|r| r.to_response()).collect())
}

/// 获取单个 Webhook 订阅
pub async fn get_subscription(
    db: &PgPool,
    account_id: &str,
    subscription_id: &str,
) -> SaasResult<WebhookSubscription> {
    let row: Option<WebhookSubscriptionRow> = sqlx::query_as(
        "SELECT id, account_id, url, secret, events, enabled, created_at, updated_at
         FROM webhook_subscriptions WHERE id = $1 AND account_id = $2"
    )
    .bind(subscription_id)
    .bind(account_id)
    .fetch_optional(db)
    .await?;

    Ok(row
        .ok_or_else(|| SaasError::NotFound("Webhook 订阅不存在".into()))?
        .to_response())
}

/// 更新 Webhook 订阅
pub async fn update_subscription(
    db: &PgPool,
    account_id: &str,
    subscription_id: &str,
    req: &UpdateWebhookRequest,
) -> SaasResult<WebhookSubscription> {
    let existing = get_subscription(db, account_id, subscription_id).await?;
    let now = chrono::Utc::now().to_rfc3339();

    let url = req.url.as_deref().unwrap_or(&existing.url);
    let events = req.events.as_deref().unwrap_or(&existing.events);
    let enabled = req.enabled.unwrap_or(existing.enabled);

    sqlx::query(
        "UPDATE webhook_subscriptions SET url = $1, events = $2, enabled = $3, updated_at = $4
         WHERE id = $5 AND account_id = $6"
    )
    .bind(url)
    .bind(events)
    .bind(enabled)
    .bind(&now)
    .bind(subscription_id)
    .bind(account_id)
    .execute(db)
    .await?;

    get_subscription(db, account_id, subscription_id).await
}

/// 删除 Webhook 订阅
pub async fn delete_subscription(
    db: &PgPool,
    account_id: &str,
    subscription_id: &str,
) -> SaasResult<()> {
    let result = sqlx::query(
        "DELETE FROM webhook_subscriptions WHERE id = $1 AND account_id = $2"
    )
    .bind(subscription_id)
    .bind(account_id)
    .execute(db)
    .await?;

    if result.rows_affected() == 0 {
        return Err(SaasError::NotFound("Webhook 订阅不存在".into()));
    }
    Ok(())
}

/// 列出订阅的投递日志
pub async fn list_deliveries(
    db: &PgPool,
    account_id: &str,
    subscription_id: &str,
) -> SaasResult<Vec<WebhookDelivery>> {
    // 先验证订阅属于该账户
    let _ = get_subscription(db, account_id, subscription_id).await?;

    let rows: Vec<WebhookDeliveryRow> = sqlx::query_as(
        "SELECT id, subscription_id, event, payload, response_status, attempts, delivered_at, created_at
         FROM webhook_deliveries WHERE subscription_id = $1 ORDER BY created_at DESC"
    )
    .bind(subscription_id)
    .fetch_all(db)
    .await?;

    Ok(rows.iter().map(|r| r.to_response()).collect())
}

// ─── 事件触发 ─────────────────────────────────────────────────

/// 触发匹配的 webhook 订阅，创建投递记录。
///
/// 查找所有启用的、事件列表包含 `event` 的订阅，
/// 为每个订阅创建一条 `webhook_deliveries` 记录。
pub async fn trigger_webhooks(
    db: &PgPool,
    event: &str,
    payload: &serde_json::Value,
) -> SaasResult<Vec<String>> {
    let subs: Vec<SubscriptionForDeliveryRow> = sqlx::query_as(
        "SELECT id, url, secret FROM webhook_subscriptions
         WHERE enabled = true AND $1 = ANY(events)"
    )
    .bind(event)
    .fetch_all(db)
    .await?;

    let mut delivery_ids = Vec::with_capacity(subs.len());
    for sub in &subs {
        let id = uuid::Uuid::new_v4().to_string();
        let now = chrono::Utc::now().to_rfc3339();
        sqlx::query(
            "INSERT INTO webhook_deliveries (id, subscription_id, event, payload, attempts, created_at)
             VALUES ($1, $2, $3, $4, 0, $5)"
        )
        .bind(&id)
        .bind(&sub.id)
        .bind(event)
        .bind(payload)
        .bind(&now)
        .execute(db)
        .await?;

        delivery_ids.push(id);
    }

    if !delivery_ids.is_empty() {
        tracing::info!(
            event = %event,
            count = delivery_ids.len(),
            "Webhook deliveries enqueued"
        );
    }

    Ok(delivery_ids)
}

// ─── 投递查询（供 Worker 使用）────────────────────────────────

/// 获取待投递的记录（未投递且尝试次数 < max_attempts）
pub(crate) async fn fetch_pending_deliveries(
    db: &PgPool,
    max_attempts: i32,
    limit: i32,
) -> SaasResult<Vec<PendingDelivery>> {
    let rows: Vec<PendingDeliveryRow> = sqlx::query_as(
        "SELECT d.id, d.subscription_id, d.event, d.payload, d.attempts,
                s.url, s.secret
         FROM webhook_deliveries d
         JOIN webhook_subscriptions s ON s.id = d.subscription_id
         WHERE d.delivered_at IS NULL AND d.attempts < $1 AND s.enabled = true
         ORDER BY d.created_at ASC
         LIMIT $2"
    )
    .bind(max_attempts)
    .bind(limit)
    .fetch_all(db)
    .await?;

    Ok(rows.into_iter().map(|r| r.to_pending()).collect())
}

/// 记录投递结果
pub async fn record_delivery_result(
    db: &PgPool,
    delivery_id: &str,
    response_status: Option<i32>,
    response_body: Option<&str>,
    success: bool,
) -> SaasResult<()> {
    let now = chrono::Utc::now().to_rfc3339();
    if success {
        sqlx::query(
            "UPDATE webhook_deliveries SET response_status = $1, response_body = $2, delivered_at = $3, attempts = attempts + 1
             WHERE id = $4"
        )
        .bind(response_status)
        .bind(response_body)
        .bind(&now)
        .bind(delivery_id)
        .execute(db)
        .await?;
    } else {
        sqlx::query(
            "UPDATE webhook_deliveries SET response_status = $1, response_body = $2, attempts = attempts + 1
             WHERE id = $3"
        )
        .bind(response_status)
        .bind(response_body)
        .bind(delivery_id)
        .execute(db)
        .await?;
    }
    Ok(())
}

// ─── 内部类型 ──────────────────────────────────────────────────

#[derive(Debug, FromRow)]
struct PendingDeliveryRow {
    id: String,
    subscription_id: String,
    event: String,
    payload: serde_json::Value,
    attempts: i32,
    url: String,
    secret: String,
}

#[allow(dead_code)]
pub(crate) struct PendingDelivery {
    pub id: String,
    pub subscription_id: String,
    pub event: String,
    pub payload: serde_json::Value,
    pub attempts: i32,
    pub url: String,
    pub secret: String,
}

impl PendingDeliveryRow {
    fn to_pending(self) -> PendingDelivery {
        PendingDelivery {
            id: self.id,
            subscription_id: self.subscription_id,
            event: self.event,
            payload: self.payload,
            attempts: self.attempts,
            url: self.url,
            secret: self.secret,
        }
    }
}

/// 生成 32 字节随机签名密钥（hex 编码）
fn generate_secret() -> String {
    use rand::RngCore;
    let mut buf = [0u8; 32];
    rand::thread_rng().fill_bytes(&mut buf);
    hex::encode(buf)
}