use uuid::Uuid;

use crate::error::AppError;
use crate::models::common::Role;
use crate::models::issues::{IssueLabel, IssueLabelRelation};
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 CreateLabelParams {
    pub name: String,
    pub color: String,
    pub description: Option<String>,
}

#[derive(serde::Deserialize, serde::Serialize, Clone, Debug, utoipa::ToSchema)]
pub struct UpdateLabelParams {
    pub name: Option<String>,
    pub color: Option<String>,
    pub description: Option<String>,
}

impl IssueService {
    pub(crate) async fn resolve_repo_id(
        &self,
        wk_name: &str,
        repo_name: &str,
    ) -> Result<Uuid, AppError> {
        let ws = self.resolve_workspace(wk_name).await?;
        crate::models::repos::Repo::find_by_name(self.ctx.db.reader(), ws.id, repo_name)
            .await
            .map_err(AppError::Database)?
            .map(|r| r.id)
            .ok_or(AppError::NotFound("repo not found".into()))
    }

    pub(crate) async fn ensure_repo_role(
        &self,
        repo_id: Uuid,
        user_uid: Uuid,
        min: Role,
    ) -> Result<(), AppError> {
        let repo = crate::models::repos::Repo::find_by_id(self.ctx.db.reader(), repo_id)
            .await
            .map_err(AppError::Database)?
            .ok_or(AppError::NotFound("repo not found".into()))?;
        let role = crate::models::repos::Repo::user_role(
            self.ctx.db.reader(),
            repo.id,
            user_uid,
            repo.owner_id,
        )
        .await
        .map_err(AppError::Database)?
        .unwrap_or(Role::Unknown);
        if crate::service::util::role_level(role) < crate::service::util::role_level(min) {
            return Err(AppError::Unauthorized);
        }
        Ok(())
    }

    pub async fn issue_labels(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
    ) -> Result<Vec<IssueLabel>, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo_id = self.resolve_repo_id(wk_name, repo_name).await?;
        let repo = crate::models::repos::Repo::find_by_id(self.ctx.db.reader(), repo_id)
            .await
            .map_err(AppError::Database)?
            .ok_or(AppError::NotFound("repo not found".into()))?;
        self.ensure_repo_readable(user_uid, &repo).await?;
        sqlx::query_as::<_, IssueLabel>(
            "SELECT id, repo_id, name, color, description, created_by, created_at, updated_at \
             FROM issue_label WHERE repo_id = $1 ORDER BY name ASC",
        )
        .bind(repo_id)
        .fetch_all(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)
    }

    pub async fn issue_create_label(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        params: CreateLabelParams,
    ) -> Result<IssueLabel, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo_id = self.resolve_repo_id(wk_name, repo_name).await?;
        self.ensure_repo_role(repo_id, user_uid, Role::Member)
            .await?;
        let name = required_text(params.name, "name")?;
        let color = required_text(params.color, "color")?;
        let now = chrono::Utc::now();
        sqlx::query_as::<_, IssueLabel>(
            "INSERT INTO issue_label (id, repo_id, name, color, description, created_by, created_at, updated_at) \
             VALUES ($1, $2, $3, $4, $5, $6, $7, $7) \
             RETURNING id, repo_id, name, color, description, created_by, created_at, updated_at",
        )
        .bind(Uuid::now_v7()).bind(repo_id).bind(&name).bind(&color)
        .bind(params.description.as_deref()).bind(user_uid).bind(now)
        .fetch_one(self.ctx.db.writer()).await.map_err(AppError::Database)
    }

    pub async fn issue_update_label(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        label_id: Uuid,
        params: UpdateLabelParams,
    ) -> Result<IssueLabel, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo_id = self.resolve_repo_id(wk_name, repo_name).await?;
        self.ensure_repo_role(repo_id, user_uid, Role::Admin)
            .await?;
        let current = sqlx::query_as::<_, IssueLabel>(
            "SELECT id, repo_id, name, color, description, created_by, created_at, updated_at \
             FROM issue_label WHERE id = $1 AND repo_id = $2",
        )
        .bind(label_id)
        .bind(repo_id)
        .fetch_optional(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?
        .ok_or(AppError::NotFound("label not found".into()))?;

        let name = params.name.unwrap_or(current.name);
        let color = params.color.unwrap_or(current.color);
        let description = super::util::merge_optional_text(params.description, current.description);
        let now = chrono::Utc::now();
        sqlx::query_as::<_, IssueLabel>(
            "UPDATE issue_label SET name = $1, color = $2, description = $3, updated_at = $4 \
             WHERE id = $5 RETURNING id, repo_id, name, color, description, created_by, created_at, updated_at",
        )
        .bind(&name).bind(&color).bind(&description).bind(now).bind(label_id)
        .fetch_one(self.ctx.db.writer()).await.map_err(AppError::Database)
    }

    pub async fn issue_delete_label(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        label_id: Uuid,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo_id = self.resolve_repo_id(wk_name, repo_name).await?;
        self.ensure_repo_role(repo_id, user_uid, Role::Admin)
            .await?;
        let result = sqlx::query("DELETE FROM issue_label WHERE id = $1 AND repo_id = $2")
            .bind(label_id)
            .bind(repo_id)
            .execute(self.ctx.db.writer())
            .await
            .map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "label not found")
    }

    pub async fn issue_assign_label(
        &self,
        ctx: &Session,
        wk_name: &str,
        number: i64,
        label_id: Uuid,
    ) -> Result<IssueLabelRelation, 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_editable(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 rel = sqlx::query_as::<_, IssueLabelRelation>(
            "INSERT INTO issue_label_relation (id, issue_id, label_id, created_by, created_at) \
             VALUES ($1, $2, $3, $4, $5) ON CONFLICT (issue_id, label_id) DO NOTHING \
             RETURNING id, issue_id, label_id, created_by, created_at",
        )
        .bind(Uuid::now_v7())
        .bind(issue_id)
        .bind(label_id)
        .bind(user_uid)
        .bind(now)
        .fetch_optional(&mut *txn)
        .await
        .map_err(AppError::Database)?
        .ok_or(AppError::Conflict("label already assigned".into()))?;
        sqlx::query("UPDATE issue_stats SET labels_count = labels_count + 1, 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(rel)
    }

    pub async fn issue_unassign_label(
        &self,
        ctx: &Session,
        wk_name: &str,
        number: i64,
        label_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;
        self.ensure_issue_editable(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("DELETE FROM issue_label_relation WHERE issue_id = $1 AND label_id = $2")
                .bind(issue_id)
                .bind(label_id)
                .execute(&mut *txn)
                .await
                .map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "label not assigned")?;
        sqlx::query("UPDATE issue_stats SET labels_count = GREATEST(labels_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(())
    }

    pub async fn issue_label_relations(
        &self,
        ctx: &Session,
        wk_name: &str,
        number: i64,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<IssueLabelRelation>, 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::<_, IssueLabelRelation>(
            "SELECT id, issue_id, label_id, created_by, created_at \
             FROM issue_label_relation WHERE issue_id = $1 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)
    }
}