use uuid::Uuid;

use crate::error::AppError;
use crate::models::issues::IssueComment;
use crate::service::IssueService;
use crate::session::Session;

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

#[derive(serde::Deserialize, serde::Serialize, Clone, Debug, utoipa::ToSchema)]
pub struct CreateCommentParams {
    pub body: String,
    pub reply_to_comment_id: Option<Uuid>,
}

#[derive(serde::Deserialize, serde::Serialize, Clone, Debug, utoipa::ToSchema)]
pub struct UpdateCommentParams {
    pub body: String,
}

impl IssueService {
    pub async fn issue_comments(
        &self,
        ctx: &Session,
        wk_name: &str,
        number: i64,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<IssueComment>, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let issue = self.resolve_issue(wk_name, number).await?;
        let issue_id = issue.id;
        self.ensure_issue_readable(user_uid, &issue).await?;
        let (limit, offset) = clamp_limit_offset(limit, offset);
        sqlx::query_as::<_, IssueComment>(
            "SELECT id, issue_id, author_id, body, reply_to_comment_id, edited_at, deleted_at, \
             created_at, updated_at FROM issue_comment \
             WHERE issue_id = $1 AND deleted_at IS NULL ORDER BY created_at ASC LIMIT $2 OFFSET $3",
        )
        .bind(issue_id)
        .bind(limit)
        .bind(offset)
        .fetch_all(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)
    }

    pub async fn issue_create_comment(
        &self,
        ctx: &Session,
        wk_name: &str,
        number: i64,
        params: CreateCommentParams,
    ) -> Result<IssueComment, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let issue = self.resolve_issue(wk_name, number).await?;
        let issue_id = issue.id;
        self.ensure_issue_readable(user_uid, &issue).await?;

        if issue.locked {
            self.ensure_issue_editable(user_uid, &issue).await?;
        }

        let body = required_text(params.body, "body")?;
        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 comment = sqlx::query_as::<_, IssueComment>(
            "INSERT INTO issue_comment (id, issue_id, author_id, body, reply_to_comment_id, \
             edited_at, deleted_at, created_at, updated_at) \
             VALUES ($1, $2, $3, $4, $5, NULL, NULL, $6, $6) \
             RETURNING id, issue_id, author_id, body, reply_to_comment_id, edited_at, deleted_at, \
             created_at, updated_at",
        )
        .bind(Uuid::now_v7())
        .bind(issue_id)
        .bind(user_uid)
        .bind(&body)
        .bind(params.reply_to_comment_id)
        .bind(now)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        sqlx::query(
            "UPDATE issue_stats SET comments_count = comments_count + 1, \
             last_commented_at = $1, updated_at = $1 WHERE issue_id = $2",
        )
        .bind(now)
        .bind(issue_id)
        .execute(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        let is_subscribed: bool = sqlx::query_scalar(
            "SELECT EXISTS(SELECT 1 FROM issue_subscriber WHERE issue_id = $1 AND user_id = $2)",
        )
        .bind(issue_id)
        .bind(user_uid)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        if !is_subscribed {
            sqlx::query(
                "INSERT INTO issue_subscriber (id, issue_id, user_id, reason, muted, created_at, updated_at) \
                 VALUES ($1, $2, $3, 'participant', false, $4, $4) ON CONFLICT DO NOTHING",
            )
            .bind(Uuid::now_v7()).bind(issue_id).bind(user_uid).bind(now)
            .execute(&mut *txn).await.map_err(AppError::Database)?;
        }

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

    pub async fn issue_update_comment(
        &self,
        ctx: &Session,
        wk_name: &str,
        number: i64,
        comment_id: Uuid,
        params: UpdateCommentParams,
    ) -> Result<IssueComment, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let issue = self.resolve_issue(wk_name, number).await?;
        let issue_id = issue.id;
        self.ensure_issue_readable(user_uid, &issue).await?;

        let body = required_text(params.body, "body")?;
        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_as::<_, IssueComment>(
            "UPDATE issue_comment SET body = $1, edited_at = $2, updated_at = $2 \
             WHERE id = $3 AND issue_id = $4 AND author_id = $5 AND deleted_at IS NULL \
             RETURNING id, issue_id, author_id, body, reply_to_comment_id, edited_at, deleted_at, \
             created_at, updated_at",
        )
        .bind(&body)
        .bind(now)
        .bind(comment_id)
        .bind(issue_id)
        .bind(user_uid)
        .fetch_optional(&mut *txn)
        .await
        .map_err(AppError::Database)?
        .ok_or(AppError::NotFound(
            "comment not found or not authored by you".into(),
        ))?;

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

    pub async fn issue_delete_comment(
        &self,
        ctx: &Session,
        wk_name: &str,
        number: i64,
        comment_id: Uuid,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let issue = self.resolve_issue(wk_name, number).await?;
        let issue_id = issue.id;

        let comment = sqlx::query_as::<_, IssueComment>(
            "SELECT id, issue_id, author_id, body, reply_to_comment_id, edited_at, deleted_at, \
             created_at, updated_at FROM issue_comment WHERE id = $1 AND issue_id = $2 AND deleted_at IS NULL",
        )
        .bind(comment_id).bind(issue_id).fetch_optional(self.ctx.db.reader()).await
        .map_err(AppError::Database)?.ok_or(AppError::NotFound("comment not found".into()))?;

        if comment.author_id != user_uid {
            self.ensure_issue_admin(user_uid, &issue).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(
            "UPDATE issue_comment SET deleted_at = $1, updated_at = $1 WHERE id = $2 AND deleted_at IS NULL",
        )
        .bind(now).bind(comment_id).execute(&mut *txn).await.map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "comment not found")?;

        sqlx::query(
            "UPDATE issue_stats SET comments_count = GREATEST(comments_count - 1, 0), updated_at = $1 WHERE issue_id = $2",
        )
        .bind(now).bind(issue_id).execute(&mut *txn).await.map_err(AppError::Database)?;

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