use uuid::Uuid;

use crate::error::AppError;
use crate::models::prs::PrAssignee;
use crate::service::PrService;
use crate::session::Session;

use super::util::{clamp_limit_offset, ensure_affected};

impl PrService {
    pub async fn pr_assignees(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        number: i64,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<PrAssignee>, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let pr = self.resolve_pr(wk_name, repo_name, number).await?;
        self.ensure_pr_readable(user_uid, &pr).await?;
        let (limit, offset) = clamp_limit_offset(limit, offset);
        sqlx::query_as::<_, PrAssignee>(
            "SELECT id, pull_request_id, assignee_id, assigned_by, created_at \
             FROM pr_assignee WHERE pull_request_id = $1 ORDER BY created_at ASC LIMIT $2 OFFSET $3",
        )
        .bind(pr.id).bind(limit).bind(offset)
        .fetch_all(self.ctx.db.reader()).await.map_err(AppError::Database)
    }

    pub async fn pr_assign(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        number: i64,
        assignee_id: Uuid,
    ) -> Result<PrAssignee, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let pr = self.resolve_pr(wk_name, repo_name, number).await?;
        self.ensure_pr_editable(user_uid, &pr).await?;
        let now = chrono::Utc::now();
        let mut txn = self
            .ctx
            .db
            .writer()
            .begin()
            .await
            .map_err(|_| AppError::TxnError)?;
        sqlx::query("SET LOCAL app.current_user_id = $1")
            .bind(user_uid)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        let assignee = sqlx::query_as::<_, PrAssignee>(
            "INSERT INTO pr_assignee (id, pull_request_id, assignee_id, assigned_by, created_at) \
             VALUES ($1, $2, $3, $4, $5) ON CONFLICT (pull_request_id, assignee_id) DO NOTHING \
             RETURNING id, pull_request_id, assignee_id, assigned_by, created_at",
        )
        .bind(Uuid::now_v7())
        .bind(pr.id)
        .bind(assignee_id)
        .bind(user_uid)
        .bind(now)
        .fetch_optional(&mut *txn)
        .await
        .map_err(AppError::Database)?
        .ok_or(AppError::Conflict("user already assigned".into()))?;

        sqlx::query(
            "INSERT INTO pr_subscription (id, pull_request_id, user_id, reason, muted, created_at, updated_at) \
             VALUES ($1, $2, $3, 'assignee', false, $4, $4) ON CONFLICT DO NOTHING",
        )
        .bind(Uuid::now_v7()).bind(pr.id).bind(assignee_id).bind(now)
        .execute(&mut *txn).await.map_err(AppError::Database)?;

        txn.commit().await.map_err(|_| AppError::TxnError)?;
        Ok(assignee)
    }

    pub async fn pr_unassign(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        number: i64,
        assignee_id: Uuid,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let pr = self.resolve_pr(wk_name, repo_name, number).await?;
        self.ensure_pr_editable(user_uid, &pr).await?;
        let mut txn = self
            .ctx
            .db
            .writer()
            .begin()
            .await
            .map_err(|_| AppError::TxnError)?;
        sqlx::query("SET LOCAL app.current_user_id = $1")
            .bind(user_uid)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        let result =
            sqlx::query("DELETE FROM pr_assignee WHERE pull_request_id = $1 AND assignee_id = $2")
                .bind(pr.id)
                .bind(assignee_id)
                .execute(&mut *txn)
                .await
                .map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "assignee not found")?;

        txn.commit().await.map_err(|_| AppError::TxnError)?;
        Ok(())
    }
}