use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::error::AppError;
use crate::models::common::Role;
use crate::models::repos::RepoMember;
use crate::service::RepoService;
use crate::session::Session;

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

#[derive(Deserialize, Serialize, Clone, Debug, utoipa::ToSchema)]
pub struct AddRepoMemberParams {
    pub user_id: Uuid,
    pub role: Option<String>,
}

#[derive(Deserialize, Serialize, Clone, Debug, utoipa::ToSchema)]
pub struct UpdateRepoMemberRoleParams {
    pub role: String,
}

impl RepoService {
    pub async fn repo_members(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<RepoMember>, 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::<_, RepoMember>(
            "SELECT id, repo_id, user_id, role, status, invited_by, joined_at, last_active_at, created_at, updated_at FROM repo_member WHERE repo_id = $1 AND status = 'active' ORDER BY created_at ASC LIMIT $2 OFFSET $3",
        )
        .bind(repo_id)
        .bind(limit)
        .bind(offset)
        .fetch_all(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)
    }

    pub async fn repo_add_member(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        params: AddRepoMemberParams,
    ) -> Result<RepoMember, 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 actor_role = self
            .ensure_repo_role_at_least(user_uid, &repo, Role::Admin)
            .await?;

        let target_workspace_member = sqlx::query_scalar::<_, bool>(
            "SELECT EXISTS(SELECT 1 FROM workspace_member WHERE workspace_id = $1 AND user_id = $2 AND status = 'active')",
        )
        .bind(repo.workspace_id)
        .bind(params.user_id)
        .fetch_one(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?;
        if !target_workspace_member {
            return Err(AppError::BadRequest(
                "user must be a workspace member".into(),
            ));
        }

        let existing = sqlx::query_scalar::<_, bool>(
            "SELECT EXISTS(SELECT 1 FROM repo_member WHERE repo_id = $1 AND user_id = $2)",
        )
        .bind(repo_id)
        .bind(params.user_id)
        .fetch_one(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?;

        if existing {
            return Err(AppError::Conflict("user is already a member".into()));
        }

        let role = params
            .role
            .as_deref()
            .and_then(|r| r.parse::<Role>().ok())
            .unwrap_or_else(|| "member".to_string().parse().unwrap_or(Role::Member));

        if role == Role::Owner {
            return Err(AppError::BadRequest("cannot add member as owner".into()));
        }
        if role == Role::Unknown {
            return Err(AppError::BadRequest("invalid role".into()));
        }
        if role_level(actor_role) < role_level(Role::Owner)
            && role_level(role) >= role_level(actor_role)
        {
            return Err(AppError::BadRequest(
                "cannot assign role equal or higher than your own".into(),
            ));
        }

        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 member = sqlx::query_as::<_, RepoMember>(
            "INSERT INTO repo_member (id, repo_id, user_id, role, status, invited_by, joined_at, created_at, updated_at) \
             VALUES ($1, $2, $3, $4, 'active', $5, $6, $6, $6) RETURNING id, repo_id, user_id, role, status, invited_by, joined_at, last_active_at, created_at, updated_at",
        )
        .bind(Uuid::now_v7())
        .bind(repo_id)
        .bind(params.user_id)
        .bind(role.to_string())
        .bind(user_uid)
        .bind(now)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

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

    pub async fn repo_update_member_role(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        member_id: Uuid,
        params: UpdateRepoMemberRoleParams,
    ) -> Result<RepoMember, 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 actor_role = self
            .ensure_repo_role_at_least(user_uid, &repo, Role::Admin)
            .await?;

        let new_role = params
            .role
            .parse::<Role>()
            .map_err(|_| AppError::BadRequest("invalid role".into()))?;
        if new_role == Role::Owner {
            return Err(AppError::BadRequest(
                "use repo_transfer_owner to change owner".into(),
            ));
        }
        if new_role == Role::Unknown {
            return Err(AppError::BadRequest("invalid role".into()));
        }

        let target = sqlx::query_as::<_, RepoMember>(
            "SELECT id, repo_id, user_id, role, status, invited_by, joined_at, last_active_at, created_at, updated_at FROM repo_member WHERE id = $1 AND repo_id = $2",
        )
        .bind(member_id)
        .bind(repo_id)
        .fetch_optional(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?
        .ok_or(AppError::NotFound("member not found".into()))?;

        if target.role == Role::Owner {
            return Err(AppError::BadRequest("cannot change owner role".into()));
        }
        if role_level(actor_role) <= role_level(target.role) && actor_role != Role::Owner {
            return Err(AppError::BadRequest(
                "cannot change role of member with equal or higher role".into(),
            ));
        }

        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 result = sqlx::query_as::<_, RepoMember>(
            "UPDATE repo_member SET role = $1, updated_at = $2 WHERE id = $3 AND repo_id = $4 RETURNING id, repo_id, user_id, role, status, invited_by, joined_at, last_active_at, created_at, updated_at",
        )
        .bind(new_role.to_string())
        .bind(now)
        .bind(member_id)
        .bind(repo_id)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

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

    pub async fn repo_remove_member(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        member_id: Uuid,
    ) -> 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 actor_role = self
            .ensure_repo_role_at_least(user_uid, &repo, Role::Admin)
            .await?;

        let target = sqlx::query_as::<_, RepoMember>(
            "SELECT id, repo_id, user_id, role, status, invited_by, joined_at, last_active_at, created_at, updated_at FROM repo_member WHERE id = $1 AND repo_id = $2",
        )
        .bind(member_id)
        .bind(repo_id)
        .fetch_optional(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?
        .ok_or(AppError::NotFound("member not found".into()))?;

        if target.role == Role::Owner {
            return Err(AppError::BadRequest(
                "cannot remove owner; transfer ownership first".into(),
            ));
        }
        if role_level(actor_role) <= role_level(target.role) && actor_role != Role::Owner {
            return Err(AppError::BadRequest(
                "cannot remove a member with equal or higher role".into(),
            ));
        }

        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 repo_member WHERE id = $1 AND repo_id = $2")
            .bind(member_id)
            .bind(repo_id)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "member not found")?;

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

    pub async fn repo_leave(
        &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;

        if repo.owner_id == user_uid {
            return Err(AppError::BadRequest(
                "owner cannot leave; transfer ownership first".into(),
            ));
        }

        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 repo_member WHERE repo_id = $1 AND user_id = $2")
            .bind(repo_id)
            .bind(user_uid)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "not a member")?;

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