use axum::Json;
use axum::extract::{Path, Query, State};
use axum::http::StatusCode;
use uuid::Uuid;
use validator::Validate;

use crate::error::{ApiError, ApiResult};
use crate::models::item::{CreateItemRequest, Item, ItemPage, ItemResponse, UpdateItemRequest};
use crate::models::pagination::PaginationQuery;
use crate::state::AppState;

/// List items, newest first.
#[utoipa::path(
    get,
    path = "/api/v1/items",
    tag = "items",
    params(PaginationQuery),
    responses(
        (status = 200, description = "Paged item list", body = ItemPage)
    )
)]
pub async fn list_items(
    State(state): State<AppState>,
    Query(query): Query<PaginationQuery>,
) -> ApiResult<Json<ItemPage>> {
    let query = query.sanitize();
    let total =
        sqlx::query_scalar::<_, i64>("SELECT COUNT(*) FROM items").fetch_one(state.db()).await?;

    let items = sqlx::query_as::<_, Item>(
        r#"
        SELECT id, name, description, created_at, updated_at
        FROM items
        ORDER BY created_at DESC
        LIMIT $1 OFFSET $2
        "#,
    )
    .bind(query.limit())
    .bind(query.offset())
    .fetch_all(state.db())
    .await?;

    Ok(Json(ItemPage {
        items: items.into_iter().map(ItemResponse::from).collect(),
        page: query.page,
        per_page: query.per_page,
        total,
    }))
}

/// Fetch a single item.
#[utoipa::path(
    get,
    path = "/api/v1/items/{id}",
    tag = "items",
    params(("id" = Uuid, Path, description = "Item id")),
    responses(
        (status = 200, description = "Item", body = ItemResponse),
        (status = 404, description = "Missing item", body = crate::error::ErrorBody)
    )
)]
pub async fn get_item(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> ApiResult<Json<ItemResponse>> {
    let item = sqlx::query_as::<_, Item>(
        r#"
        SELECT id, name, description, created_at, updated_at
        FROM items
        WHERE id = $1
        "#,
    )
    .bind(id)
    .fetch_optional(state.db())
    .await?
    .ok_or_else(|| ApiError::NotFound(format!("item {id} not found")))?;

    Ok(Json(item.into()))
}

/// Create an item.
#[utoipa::path(
    post,
    path = "/api/v1/items",
    tag = "items",
    request_body = CreateItemRequest,
    responses(
        (status = 201, description = "Created item", body = ItemResponse),
        (status = 400, description = "Validation error", body = crate::error::ErrorBody)
    )
)]
pub async fn create_item(
    State(state): State<AppState>,
    Json(body): Json<CreateItemRequest>,
) -> ApiResult<(StatusCode, Json<ItemResponse>)> {
    body.validate().map_err(|err| ApiError::Validation(err.to_string()))?;

    let item = sqlx::query_as::<_, Item>(
        r#"
        INSERT INTO items (name, description)
        VALUES ($1, $2)
        RETURNING id, name, description, created_at, updated_at
        "#,
    )
    .bind(body.name.trim())
    .bind(body.description.as_deref())
    .fetch_one(state.db())
    .await?;

    Ok((StatusCode::CREATED, Json(item.into())))
}

/// Replace selected item fields.
#[utoipa::path(
    patch,
    path = "/api/v1/items/{id}",
    tag = "items",
    params(("id" = Uuid, Path, description = "Item id")),
    request_body = UpdateItemRequest,
    responses(
        (status = 200, description = "Updated item", body = ItemResponse),
        (status = 404, description = "Missing item", body = crate::error::ErrorBody)
    )
)]
pub async fn update_item(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
    Json(body): Json<UpdateItemRequest>,
) -> ApiResult<Json<ItemResponse>> {
    body.validate().map_err(|err| ApiError::Validation(err.to_string()))?;

    let item = sqlx::query_as::<_, Item>(
        r#"
        UPDATE items
        SET
            name = COALESCE($2, name),
            description = COALESCE($3, description),
            updated_at = now()
        WHERE id = $1
        RETURNING id, name, description, created_at, updated_at
        "#,
    )
    .bind(id)
    .bind(body.name.as_deref().map(str::trim))
    .bind(body.description.as_deref())
    .fetch_optional(state.db())
    .await?
    .ok_or_else(|| ApiError::NotFound(format!("item {id} not found")))?;

    Ok(Json(item.into()))
}

/// Delete an item.
#[utoipa::path(
    delete,
    path = "/api/v1/items/{id}",
    tag = "items",
    params(("id" = Uuid, Path, description = "Item id")),
    responses(
        (status = 204, description = "Deleted"),
        (status = 404, description = "Missing item", body = crate::error::ErrorBody)
    )
)]
pub async fn delete_item(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> ApiResult<StatusCode> {
    let result =
        sqlx::query("DELETE FROM items WHERE id = $1").bind(id).execute(state.db()).await?;
    if result.rows_affected() == 0 {
        return Err(ApiError::NotFound(format!("item {id} not found")));
    }
    Ok(StatusCode::NO_CONTENT)
}