use uuid::Uuid;

use crate::error::AppError;
use crate::models::repos::RepoStar;
use crate::service::RepoService;
use crate::session::Session;

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

impl RepoService {
    pub async fn repo_star(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo = self.resolve_repo(wk_name, repo_name).await?;
        let repo_id = repo.id;
        self.ensure_repo_readable(user_uid, &repo).await?;

        let now = chrono::Utc::now();
        let mut txn = self
            .ctx
            .db
            .writer()
            .begin()
            .await
            .map_err(|_| AppError::TxnError)?;
        sqlx::query(set_local_user_id(user_uid))
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        let result = sqlx::query(
            "INSERT INTO repo_star (id, repo_id, user_id, created_at) VALUES ($1, $2, $3, $4) ON CONFLICT (repo_id, user_id) DO NOTHING",
        )
        .bind(Uuid::now_v7())
        .bind(repo_id)
        .bind(user_uid)
        .bind(now)
        .execute(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        // Only increment stars_count if the INSERT actually happened
        if result.rows_affected() > 0 {
            sqlx::query(
                "UPDATE repo_stats SET stars_count = stars_count + 1, updated_at = $1 WHERE repo_id = $2",
            )
            .bind(now)
            .bind(repo_id)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;
        }

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

    pub async fn repo_unstar(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo = self.resolve_repo(wk_name, repo_name).await?;
        let repo_id = repo.id;

        let now = chrono::Utc::now();
        let mut txn = self
            .ctx
            .db
            .writer()
            .begin()
            .await
            .map_err(|_| AppError::TxnError)?;
        sqlx::query(set_local_user_id(user_uid))
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        let result = sqlx::query("DELETE FROM repo_star WHERE repo_id = $1 AND user_id = $2")
            .bind(repo_id)
            .bind(user_uid)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        if result.rows_affected() > 0 {
            sqlx::query(
                "UPDATE repo_stats SET stars_count = GREATEST(stars_count - 1, 0), updated_at = $1 WHERE repo_id = $2",
            )
            .bind(now)
            .bind(repo_id)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;
        }

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

    pub async fn repo_stargazers(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<RepoStar>, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo = self.resolve_repo(wk_name, repo_name).await?;
        let repo_id = repo.id;
        self.ensure_repo_readable(user_uid, &repo).await?;
        let (limit, offset) = clamp_limit_offset(limit, offset);
        sqlx::query_as::<_, RepoStar>(
            "SELECT id, repo_id, user_id, created_at FROM repo_star WHERE repo_id = $1 ORDER BY created_at DESC LIMIT $2 OFFSET $3",
        )
        .bind(repo_id)
        .bind(limit)
        .bind(offset)
        .fetch_all(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)
    }
}