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

use crate::error::AppError;
use crate::service::im::events::{MemberAction, MemberEvent};
use crate::models::base_info::UserBaseInfo;
use crate::models::channels::ChannelMember;
use crate::models::common::Role;
use crate::models::workspaces::Workspace;
use crate::service::ImService;
use crate::service::im::events::ImEvent;

use super::session::ImSession;
use super::util::*;

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

#[derive(Deserialize, Serialize, Clone, Debug, utoipa::ToSchema)]
pub struct UpdateMemberParams {
    pub role: Option<String>,
    pub muted: Option<bool>,
    pub pinned: Option<bool>,
}

impl ImService {
    pub async fn member_list(
        &self,
        ctx: &ImSession,
        _wk_name: &str,
        channel_id: Uuid,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<ChannelMember>, AppError> {
        let user_uid = ctx.user;
        let channel = self.resolve_channel(channel_id).await?;
        self.ensure_channel_readable(user_uid, &channel).await?;
        let (limit, offset) = clamp_limit_offset(limit, offset);

        sqlx::query_as::<_, ChannelMember>(
            "SELECT id, channel_id, user_id, role, status, muted, pinned, \
             last_read_message_id, last_read_at, joined_at, left_at, created_at, updated_at \
             FROM channel_member WHERE channel_id = $1 AND status = 'active' \
             ORDER BY joined_at ASC LIMIT $2 OFFSET $3",
        )
        .bind(channel_id)
        .bind(limit)
        .bind(offset)
        .fetch_all(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)
    }

    pub async fn member_invite(
        &self,
        ctx: &ImSession,
        _wk_name: &str,
        channel_id: Uuid,
        params: InviteMemberParams,
    ) -> Result<ChannelMember, AppError> {
        let user_uid = ctx.user;
        let channel = self.resolve_channel(channel_id).await?;
        self.ensure_channel_editable(user_uid, &channel).await?;

        let ws = Workspace::find_by_id(self.ctx.db.reader(), channel.workspace_id)
            .await
            .map_err(AppError::Database)?
            .ok_or(AppError::NotFound("workspace not found".into()))?;
        let ws_role =
            Workspace::user_role(self.ctx.db.reader(), ws.id, params.user_id, ws.owner_id)
                .await
                .map_err(AppError::Database)?;
        if ws_role == Some(Role::Unknown) || ws_role.is_none() {
            return Err(AppError::BadRequest(
                "invited user is not a workspace member".into(),
            ));
        }

        let is_already = self.is_channel_member(channel_id, params.user_id).await?;
        if is_already {
            return Err(AppError::Conflict("user is already a member".into()));
        }

        let role = parse_enum(params.role, Role::Member, Role::Unknown, "role")?;

        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 member = sqlx::query_as::<_, ChannelMember>(
            "INSERT INTO channel_member \
             (id, channel_id, user_id, role, status, muted, pinned, joined_at, created_at, updated_at) \
             VALUES ($1, $2, $3, $4, 'active', false, false, $5, $5, $5) \
             RETURNING id, channel_id, user_id, role, status, muted, pinned, \
              last_read_message_id, last_read_at, joined_at, left_at, created_at, updated_at",
        )
        .bind(Uuid::now_v7())
        .bind(channel_id)
        .bind(params.user_id)
        .bind(role)
        .bind(now)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        self.increment_channel_stat(channel_id, 1, now, &mut txn)
            .await?;

        txn.commit().await.map_err(|_| AppError::TxnError)?;
        tracing::info!(channel_id = %channel_id, user_id = %params.user_id, "Member invited");
        let request_id = Uuid::nil();
        let event = MemberEvent {
            channel_id,
            user: UserBaseInfo::placeholder(member.user_id),
            user_id: member.user_id,
            action: MemberAction::Joined,
        };
        self.publish(&format!("im.member.{}", channel_id), request_id, &event)
            .await;
        self.emit_event(ImEvent::Member {
            request_id,
            data: event,
        });
        Ok(member)
    }

    pub async fn member_update(
        &self,
        ctx: &ImSession,
        _wk_name: &str,
        channel_id: Uuid,
        member_user_id: Uuid,
        params: UpdateMemberParams,
    ) -> Result<ChannelMember, AppError> {
        let user_uid = ctx.user;
        let channel = self.resolve_channel(channel_id).await?;
        self.ensure_channel_admin(user_uid, &channel).await?;

        let role = match params.role {
            Some(ref v) => parse_enum(Some(v.clone()), Role::Member, Role::Unknown, "role")?,
            None => {
                // Fetch current role
                sqlx::query_scalar::<_, String>(
                    "SELECT role::text FROM channel_member \
                     WHERE channel_id = $1 AND user_id = $2 AND status = 'active'",
                )
                .bind(channel_id)
                .bind(member_user_id)
                .fetch_optional(self.ctx.db.reader())
                .await
                .map_err(AppError::Database)?
                .map(|s| s.parse::<Role>().unwrap_or(Role::Member))
                .unwrap_or(Role::Member)
            }
        };

        let now = chrono::Utc::now();
        let member = sqlx::query_as::<_, ChannelMember>(
            "UPDATE channel_member SET role = $1, muted = COALESCE($2, muted), \
             pinned = COALESCE($3, pinned), updated_at = $4 \
             WHERE channel_id = $5 AND user_id = $6 AND status = 'active' \
             RETURNING id, channel_id, user_id, role, status, muted, pinned, \
              last_read_message_id, last_read_at, joined_at, left_at, created_at, updated_at",
        )
        .bind(role)
        .bind(params.muted)
        .bind(params.pinned)
        .bind(now)
        .bind(channel_id)
        .bind(member_user_id)
        .fetch_one(self.ctx.db.writer())
        .await
        .map_err(AppError::Database)?;
        let request_id = Uuid::nil();
        let event = MemberEvent {
            channel_id,
            user: UserBaseInfo::placeholder(member.user_id),
            user_id: member.user_id,
            action: MemberAction::Updated,
        };
        self.publish(&format!("im.member.{}", channel_id), request_id, &event)
            .await;
        self.emit_event(ImEvent::Member {
            request_id,
            data: event,
        });
        Ok(member)
    }

    pub async fn member_kick(
        &self,
        ctx: &ImSession,
        _wk_name: &str,
        channel_id: Uuid,
        member_user_id: Uuid,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user;
        let channel = self.resolve_channel(channel_id).await?;
        self.ensure_channel_admin(user_uid, &channel).await?;

        if member_user_id == channel.created_by {
            return Err(AppError::Forbidden("cannot kick channel owner".into()));
        }

        let ws = Workspace::find_by_id(self.ctx.db.reader(), channel.workspace_id)
            .await
            .map_err(AppError::Database)?
            .ok_or(AppError::NotFound("workspace not found".into()))?;
        if member_user_id == ws.owner_id {
            return Err(AppError::Forbidden("cannot kick workspace owner".into()));
        }

        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 channel_member SET status = 'inactive', left_at = $1, updated_at = $1 \
             WHERE channel_id = $2 AND user_id = $3 AND status = 'active'",
        )
        .bind(now)
        .bind(channel_id)
        .bind(member_user_id)
        .execute(&mut *txn)
        .await
        .map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "member not found")?;

        self.increment_channel_stat(channel_id, -1, now, &mut txn)
            .await?;
        txn.commit().await.map_err(|_| AppError::TxnError)?;

        tracing::info!(channel_id = %channel_id, user_id = %member_user_id, "Member kicked");
        let request_id = Uuid::nil();
        let event = MemberEvent {
            channel_id,
            user: UserBaseInfo::placeholder(member_user_id),
            user_id: member_user_id,
            action: MemberAction::Kicked,
        };
        self.publish(&format!("im.member.{}", channel_id), request_id, &event)
            .await;
        self.emit_event(ImEvent::Member {
            request_id,
            data: event,
        });
        Ok(())
    }

    pub async fn member_leave(
        &self,
        ctx: &ImSession,
        _wk_name: &str,
        channel_id: Uuid,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user;
        let channel = self.resolve_channel(channel_id).await?;

        if channel.created_by == user_uid {
            return Err(AppError::Forbidden("channel owner cannot leave".into()));
        }

        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 channel_member SET status = 'inactive', left_at = $1, updated_at = $1 \
             WHERE channel_id = $2 AND user_id = $3 AND status = 'active'",
        )
        .bind(now)
        .bind(channel_id)
        .bind(user_uid)
        .execute(&mut *txn)
        .await
        .map_err(AppError::Database)?;
        ensure_affected(result.rows_affected(), "not a member")?;

        self.increment_channel_stat(channel_id, -1, now, &mut txn)
            .await?;
        txn.commit().await.map_err(|_| AppError::TxnError)?;
        let request_id = Uuid::nil();
        let event = MemberEvent {
            channel_id,
            user: UserBaseInfo::placeholder(user_uid),
            user_id: user_uid,
            action: MemberAction::Left,
        };
        self.publish(&format!("im.member.{}", channel_id), request_id, &event)
            .await;
        self.emit_event(ImEvent::Member {
            request_id,
            data: event,
        });
        Ok(())
    }

    pub async fn member_join(
        &self,
        ctx: &ImSession,
        _wk_name: &str,
        channel_id: Uuid,
    ) -> Result<ChannelMember, AppError> {
        let user_uid = ctx.user;
        let channel = self.resolve_channel(channel_id).await?;
        self.ensure_channel_readable(user_uid, &channel).await?;

        let is_already = self.is_channel_member(channel_id, user_uid).await?;
        if is_already {
            return Err(AppError::Conflict("already a member".into()));
        }

        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 member = sqlx::query_as::<_, ChannelMember>(
            "INSERT INTO channel_member \
             (id, channel_id, user_id, role, status, muted, pinned, joined_at, created_at, updated_at) \
             VALUES ($1, $2, $3, 'member', 'active', false, false, $4, $4, $4) \
             RETURNING id, channel_id, user_id, role, status, muted, pinned, \
              last_read_message_id, last_read_at, joined_at, left_at, created_at, updated_at",
        )
        .bind(Uuid::now_v7())
        .bind(channel_id)
        .bind(user_uid)
        .bind(now)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        self.increment_channel_stat(channel_id, 1, now, &mut txn)
            .await?;
        txn.commit().await.map_err(|_| AppError::TxnError)?;
        let request_id = Uuid::nil();
        let event = MemberEvent {
            channel_id,
            user: UserBaseInfo::placeholder(member.user_id),
            user_id: member.user_id,
            action: MemberAction::Joined,
        };
        self.publish(&format!("im.member.{}", channel_id), request_id, &event)
            .await;
        self.emit_event(ImEvent::Member {
            request_id,
            data: event,
        });
        Ok(member)
    }

}