//! BaseInfo structs — stable, minimal projections of core entities for API/WS responses.
//!
//! Every raw UUID foreign key in API / WebSocket responses must be expanded
//! to its corresponding `*BaseInfo` object so frontend consumers never
//! receive bare identifiers.
//!
//! Batch resolvers are provided to avoid N+1 queries when enriching
//! collections of entities.

use std::collections::HashMap;

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

use crate::error::AppError;
use crate::models::common::{ChannelType, State, Visibility};
use crate::models::db::AppDatabase;

// Section: BaseInfo structs

#[derive(Debug, Clone, Default, Serialize, Deserialize, utoipa::ToSchema)]
pub struct UserBaseInfo {
    pub id: Uuid,
    pub username: String,
    pub display_name: Option<String>,
    pub avatar_url: Option<String>,
    pub is_bot: bool,
}

#[derive(Debug, Clone, Default, Serialize, Deserialize, utoipa::ToSchema)]
pub struct WorkspaceBaseInfo {
    pub id: Uuid,
    pub name: String,
    pub avatar_url: Option<String>,
    pub visibility: Visibility,
}

#[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
pub struct RepoBaseInfo {
    pub id: Uuid,
    pub name: String,
    pub workspace_id: Uuid,
    pub visibility: Visibility,
    pub is_fork: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
pub struct ChannelBaseInfo {
    pub id: Uuid,
    pub name: String,
    pub channel_type: ChannelType,
    pub workspace_id: Uuid,
    pub archived: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
pub struct IssueBaseInfo {
    pub id: Uuid,
    pub number: i64,
    pub title: String,
    pub state: State,
    pub workspace_id: Uuid,
}

#[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
pub struct PullRequestBaseInfo {
    pub id: Uuid,
    pub number: i64,
    pub title: String,
    pub state: State,
    pub repo_id: Uuid,
}

#[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
pub struct WikiPageBaseInfo {
    pub id: Uuid,
    pub title: String,
    pub slug: String,
    pub repo_id: Uuid,
}

// Section: DB row structs for batch queries

#[derive(Debug, sqlx::FromRow)]
struct UserBaseInfoRow {
    id: Uuid,
    username: String,
    display_name: Option<String>,
    avatar_url: Option<String>,
    is_bot: bool,
}

impl From<UserBaseInfoRow> for UserBaseInfo {
    fn from(r: UserBaseInfoRow) -> Self {
        UserBaseInfo {
            id: r.id,
            username: r.username,
            display_name: r.display_name,
            avatar_url: r.avatar_url,
            is_bot: r.is_bot,
        }
    }
}

#[derive(Debug, sqlx::FromRow)]
struct WorkspaceBaseInfoRow {
    id: Uuid,
    name: String,
    avatar_url: Option<String>,
    visibility: Visibility,
}

impl From<WorkspaceBaseInfoRow> for WorkspaceBaseInfo {
    fn from(r: WorkspaceBaseInfoRow) -> Self {
        WorkspaceBaseInfo {
            id: r.id,
            name: r.name,
            avatar_url: r.avatar_url,
            visibility: r.visibility,
        }
    }
}

#[derive(Debug, sqlx::FromRow)]
struct RepoBaseInfoRow {
    id: Uuid,
    name: String,
    workspace_id: Uuid,
    visibility: Visibility,
    is_fork: bool,
}

impl From<RepoBaseInfoRow> for RepoBaseInfo {
    fn from(r: RepoBaseInfoRow) -> Self {
        RepoBaseInfo {
            id: r.id,
            name: r.name,
            workspace_id: r.workspace_id,
            visibility: r.visibility,
            is_fork: r.is_fork,
        }
    }
}

#[derive(Debug, sqlx::FromRow)]
struct ChannelBaseInfoRow {
    id: Uuid,
    name: String,
    channel_type: ChannelType,
    workspace_id: Uuid,
    archived: bool,
}

impl From<ChannelBaseInfoRow> for ChannelBaseInfo {
    fn from(r: ChannelBaseInfoRow) -> Self {
        ChannelBaseInfo {
            id: r.id,
            name: r.name,
            channel_type: r.channel_type,
            workspace_id: r.workspace_id,
            archived: r.archived,
        }
    }
}

#[derive(Debug, sqlx::FromRow)]
struct IssueBaseInfoRow {
    id: Uuid,
    number: i64,
    title: String,
    state: State,
    workspace_id: Uuid,
}

impl From<IssueBaseInfoRow> for IssueBaseInfo {
    fn from(r: IssueBaseInfoRow) -> Self {
        IssueBaseInfo {
            id: r.id,
            number: r.number,
            title: r.title,
            state: r.state,
            workspace_id: r.workspace_id,
        }
    }
}

#[derive(Debug, sqlx::FromRow)]
struct PullRequestBaseInfoRow {
    id: Uuid,
    number: i64,
    title: String,
    state: State,
    repo_id: Uuid,
}

impl From<PullRequestBaseInfoRow> for PullRequestBaseInfo {
    fn from(r: PullRequestBaseInfoRow) -> Self {
        PullRequestBaseInfo {
            id: r.id,
            number: r.number,
            title: r.title,
            state: r.state,
            repo_id: r.repo_id,
        }
    }
}

impl UserBaseInfo {
    pub fn placeholder(id: Uuid) -> Self {
        Self {
            id,
            username: "unknown".into(),
            display_name: Some("Unknown User".into()),
            avatar_url: None,
            is_bot: false,
        }
    }
}

// Section: Batch resolvers

/// Resolve multiple users to `UserBaseInfo`.  Always do a single
/// `SELECT … WHERE id = ANY($1)` to avoid N+1.
pub async fn resolve_users(
    db: &AppDatabase,
    ids: &[Uuid],
) -> Result<HashMap<Uuid, UserBaseInfo>, AppError> {
    if ids.is_empty() {
        return Ok(HashMap::new());
    }
    let rows = sqlx::query_as::<_, UserBaseInfoRow>(
        r#"SELECT id, username, display_name, avatar_url, is_bot
           FROM "user" WHERE id = ANY($1) AND deleted_at IS NULL"#,
    )
    .bind(ids)
    .fetch_all(db.reader())
    .await
    .map_err(AppError::Database)?;
    Ok(rows.into_iter().map(|r| (r.id, r.into())).collect())
}

/// Resolve multiple workspaces to `WorkspaceBaseInfo`.
pub async fn resolve_workspaces(
    db: &AppDatabase,
    ids: &[Uuid],
) -> Result<HashMap<Uuid, WorkspaceBaseInfo>, AppError> {
    if ids.is_empty() {
        return Ok(HashMap::new());
    }
    let rows = sqlx::query_as::<_, WorkspaceBaseInfoRow>(
        "SELECT id, name, avatar_url, visibility FROM workspace WHERE id = ANY($1) AND deleted_at IS NULL",
    )
    .bind(ids)
    .fetch_all(db.reader())
    .await
    .map_err(AppError::Database)?;
    Ok(rows.into_iter().map(|r| (r.id, r.into())).collect())
}

/// Resolve multiple repos to `RepoBaseInfo`.
pub async fn resolve_repos(
    db: &AppDatabase,
    ids: &[Uuid],
) -> Result<HashMap<Uuid, RepoBaseInfo>, AppError> {
    if ids.is_empty() {
        return Ok(HashMap::new());
    }
    let rows = sqlx::query_as::<_, RepoBaseInfoRow>(
        "SELECT id, name, workspace_id, visibility, is_fork FROM repo WHERE id = ANY($1) AND deleted_at IS NULL",
    )
    .bind(ids)
    .fetch_all(db.reader())
    .await
    .map_err(AppError::Database)?;
    Ok(rows.into_iter().map(|r| (r.id, r.into())).collect())
}

/// Resolve multiple channels to `ChannelBaseInfo`.
pub async fn resolve_channels(
    db: &AppDatabase,
    ids: &[Uuid],
) -> Result<HashMap<Uuid, ChannelBaseInfo>, AppError> {
    if ids.is_empty() {
        return Ok(HashMap::new());
    }
    let rows = sqlx::query_as::<_, ChannelBaseInfoRow>(
        "SELECT id, name, channel_type, workspace_id, archived FROM channel WHERE id = ANY($1) AND deleted_at IS NULL",
    )
    .bind(ids)
    .fetch_all(db.reader())
    .await
    .map_err(AppError::Database)?;
    Ok(rows.into_iter().map(|r| (r.id, r.into())).collect())
}

/// Resolve multiple issues to `IssueBaseInfo`.
pub async fn resolve_issues(
    db: &AppDatabase,
    ids: &[Uuid],
) -> Result<HashMap<Uuid, IssueBaseInfo>, AppError> {
    if ids.is_empty() {
        return Ok(HashMap::new());
    }
    let rows = sqlx::query_as::<_, IssueBaseInfoRow>(
        "SELECT id, number, title, state, workspace_id FROM issue WHERE id = ANY($1) AND deleted_at IS NULL",
    )
    .bind(ids)
    .fetch_all(db.reader())
    .await
    .map_err(AppError::Database)?;
    Ok(rows.into_iter().map(|r| (r.id, r.into())).collect())
}

/// Resolve multiple pull requests to `PullRequestBaseInfo`.
pub async fn resolve_pull_requests(
    db: &AppDatabase,
    ids: &[Uuid],
) -> Result<HashMap<Uuid, PullRequestBaseInfo>, AppError> {
    if ids.is_empty() {
        return Ok(HashMap::new());
    }
    let rows = sqlx::query_as::<_, PullRequestBaseInfoRow>(
        "SELECT id, number, title, state, repo_id FROM pull_request WHERE id = ANY($1) AND deleted_at IS NULL",
    )
    .bind(ids)
    .fetch_all(db.reader())
    .await
    .map_err(AppError::Database)?;
    Ok(rows.into_iter().map(|r| (r.id, r.into())).collect())
}