//! Root folders (`DESIGN.md` §5.1): kind, audience, path and the one policy
//! attached. Reads serve the add flow (§9.2); writes are the settings view's.

use axum::extract::rejection::JsonRejection;
use axum::extract::{Path, State};
use axum::http::StatusCode;
use axum::Json;
use serde::{Deserialize, Serialize};
use utoipa::ToSchema;

use crate::movies::{pool, ApiError, ErrorBody};
use crate::policies::parsed;
use crate::state::AppState;

/// A root folder joined with its policy, enough for the add flow to pre-fill
/// root and policy (DESIGN.md §9.2) without a second request.
#[derive(Debug, Clone, Serialize, ToSchema)]
pub struct Root {
    pub id: i64,
    pub kind: String,
    pub audience: String,
    pub path: String,
    pub policy_id: i64,
    pub policy_name: String,
}

/// The payload for creating or replacing a root.
#[derive(Debug, Clone, Deserialize, ToSchema)]
pub struct RootInput {
    /// `movie` or `tv` — the Transmission label and layout prefix (§7.1, §7.4).
    pub kind: String,
    /// `main` or `kids`.
    pub audience: String,
    pub path: String,
    pub policy_id: i64,
}

impl RootInput {
    fn validate(&self) -> Result<(), String> {
        if self.kind != "movie" && self.kind != "tv" {
            return Err(format!("kind: '{}' is neither movie nor tv", self.kind));
        }
        if self.audience != "main" && self.audience != "kids" {
            return Err(format!(
                "audience: '{}' is neither main nor kids",
                self.audience
            ));
        }
        if self.path.trim().is_empty() {
            return Err("path: must not be empty".into());
        }
        Ok(())
    }

    async fn policy_exists(&self, state: &AppState) -> Result<(), ApiError> {
        let exists: Option<i64> =
            sqlx::query_scalar!("SELECT id FROM policies WHERE id = ?", self.policy_id)
                .fetch_optional(pool(state)?)
                .await?;
        if exists.is_none() {
            return Err(ApiError::Invalid(format!(
                "policy_id: no policy {}",
                self.policy_id
            )));
        }
        Ok(())
    }
}

async fn load_root(state: &AppState, id: i64) -> Result<Root, ApiError> {
    sqlx::query_as!(
        Root,
        r#"SELECT r.id AS "id!: i64",
                  r.kind       AS "kind!: String",
                  r.audience   AS "audience!: String",
                  r.path       AS "path!: String",
                  p.id         AS "policy_id!: i64",
                  p.name       AS "policy_name!: String"
           FROM roots r JOIN policies p ON p.id = r.policy_id
           WHERE r.id = ?"#,
        id
    )
    .fetch_optional(pool(state)?)
    .await?
    .ok_or(ApiError::RootNotFound)
}

#[utoipa::path(
    get, path = "/api/roots", tag = "roots",
    responses(
        (status = 200, body = [Root]),
        (status = 500, body = ErrorBody),
        (status = 503, body = ErrorBody)
    )
)]
pub async fn list(State(state): State<AppState>) -> Result<Json<Vec<Root>>, ApiError> {
    let roots = sqlx::query_as!(
        Root,
        r#"SELECT r.id AS "id!: i64", r.kind AS "kind!: String", r.audience AS "audience!: String", r.path AS "path!: String", p.id AS "policy_id!: i64", p.name AS "policy_name!: String" FROM roots r JOIN policies p ON p.id = r.policy_id ORDER BY r.id"#
    )
    .fetch_all(pool(&state)?)
    .await?;
    Ok(Json(roots))
}

#[utoipa::path(
    get, path = "/api/roots/{root_id}", tag = "roots",
    params(("root_id" = i64, Path, description = "Root row id")),
    responses(
        (status = 200, body = Root),
        (status = 404, body = ErrorBody),
        (status = 500, body = ErrorBody),
        (status = 503, body = ErrorBody)
    )
)]
pub async fn get(
    State(state): State<AppState>,
    Path(id): Path<i64>,
) -> Result<Json<Root>, ApiError> {
    Ok(Json(load_root(&state, id).await?))
}

#[utoipa::path(
    post, path = "/api/roots", tag = "roots", request_body = RootInput,
    responses(
        (status = 201, body = Root),
        (status = 409, body = ErrorBody),
        (status = 422, body = ErrorBody),
        (status = 500, body = ErrorBody),
        (status = 503, body = ErrorBody)
    )
)]
pub async fn create(
    State(state): State<AppState>,
    body: Result<Json<RootInput>, JsonRejection>,
) -> Result<(StatusCode, Json<Root>), ApiError> {
    let input = parsed(body)?;
    input.validate().map_err(ApiError::Invalid)?;
    input.policy_exists(&state).await?;
    let path = input.path.trim().to_owned();
    let result = sqlx::query!(
        "INSERT INTO roots (kind, audience, path, policy_id) VALUES (?, ?, ?, ?)",
        input.kind,
        input.audience,
        path,
        input.policy_id,
    )
    .execute(pool(&state)?)
    .await
    .map_err(root_conflict)?;
    let root = load_root(&state, result.last_insert_rowid()).await?;
    Ok((StatusCode::CREATED, Json(root)))
}

#[utoipa::path(
    put, path = "/api/roots/{root_id}", tag = "roots", request_body = RootInput,
    params(("root_id" = i64, Path, description = "Root row id")),
    responses(
        (status = 200, body = Root),
        (status = 404, body = ErrorBody),
        (status = 409, body = ErrorBody),
        (status = 422, body = ErrorBody),
        (status = 500, body = ErrorBody),
        (status = 503, body = ErrorBody)
    )
)]
pub async fn update(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    body: Result<Json<RootInput>, JsonRejection>,
) -> Result<Json<Root>, ApiError> {
    let input = parsed(body)?;
    input.validate().map_err(ApiError::Invalid)?;
    input.policy_exists(&state).await?;
    let path = input.path.trim().to_owned();
    let result = sqlx::query!(
        r#"UPDATE roots SET kind = ?, audience = ?, path = ?, policy_id = ?,
               updated_at = strftime('%Y-%m-%dT%H:%M:%fZ', 'now')
           WHERE id = ?"#,
        input.kind,
        input.audience,
        path,
        input.policy_id,
        id,
    )
    .execute(pool(&state)?)
    .await
    .map_err(root_conflict)?;
    if result.rows_affected() == 0 {
        return Err(ApiError::RootNotFound);
    }
    Ok(Json(load_root(&state, id).await?))
}

/// A duplicate path or a duplicate (kind, audience) pair is a settings
/// mistake the operator can fix, not a server fault.
fn root_conflict(error: sqlx::Error) -> ApiError {
    if error
        .as_database_error()
        .is_some_and(sqlx::error::DatabaseError::is_unique_violation)
    {
        return ApiError::Conflict(
            "a root with this path or this kind and audience already exists".into(),
        );
    }
    ApiError::from(error)
}

#[utoipa::path(
    delete, path = "/api/roots/{root_id}", tag = "roots",
    params(("root_id" = i64, Path, description = "Root row id")),
    responses(
        (status = 204),
        (status = 404, body = ErrorBody),
        (status = 409, body = ErrorBody),
        (status = 500, body = ErrorBody),
        (status = 503, body = ErrorBody)
    )
)]
pub async fn delete(
    State(state): State<AppState>,
    Path(id): Path<i64>,
) -> Result<StatusCode, ApiError> {
    let movies: i64 = sqlx::query_scalar!(
        r#"SELECT count(*) AS "count!: i64" FROM movies WHERE root_id = ?"#,
        id
    )
    .fetch_one(pool(&state)?)
    .await?;
    if movies > 0 {
        return Err(ApiError::Conflict(format!(
            "this root still owns {movies} movie{} — move them first",
            if movies == 1 { "" } else { "s" }
        )));
    }
    let series: i64 = sqlx::query_scalar!(
        r#"SELECT count(*) AS "count!: i64" FROM series WHERE root_id = ?"#,
        id
    )
    .fetch_one(pool(&state)?)
    .await?;
    if series > 0 {
        return Err(ApiError::Conflict(format!(
            "this root still owns {series} series — move them first"
        )));
    }
    let result = sqlx::query!("DELETE FROM roots WHERE id = ?", id)
        .execute(pool(&state)?)
        .await?;
    if result.rows_affected() == 0 {
        return Err(ApiError::RootNotFound);
    }
    Ok(StatusCode::NO_CONTENT)
}

#[cfg(test)]
mod tests {
    use crate::{router, AppState, Upstreams};
    use axum::http::StatusCode;

    async fn application() -> (tempfile::TempDir, String) {
        let dir = tempfile::tempdir().expect("tempdir");
        let database = arr_db::Db::connect(dir.path().join("arr.db"))
            .await
            .expect("database");
        database.migrate().await.expect("migrate");
        let state = AppState::new(Upstreams::new(
            "http://127.0.0.1:1".into(),
            "http://127.0.0.1:1".into(),
        ))
        .expect("state")
        .with_database(database);
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0")
            .await
            .expect("bind");
        let address = listener.local_addr().expect("address");
        let app = router(state);
        tokio::spawn(async move { axum::serve(listener, app).await.expect("serve") });
        (dir, format!("http://{address}"))
    }

    #[tokio::test]
    async fn roots_carry_their_policy_name() {
        let (_dir, base) = application().await;
        let roots: Vec<serde_json::Value> = reqwest::get(format!("{base}/api/roots"))
            .await
            .expect("roots")
            .json()
            .await
            .expect("json");
        assert_eq!(roots.len(), 4, "the seeded movie and TV roots: {roots:?}");
        assert_eq!(roots[0]["audience"], "main");
        assert_eq!(roots[0]["policy_name"], "Movies — main");
        assert_eq!(roots[1]["audience"], "kids");
        assert!(roots[1]["path"]
            .as_str()
            .is_some_and(|p| p.contains("kids")));
        assert_eq!(roots[2]["kind"], "tv");
        assert_eq!(roots[2]["policy_name"], "TV — main");
        assert_eq!(roots[3]["kind"], "tv");
        assert_eq!(roots[3]["policy_name"], "TV — kids");
    }

    fn root_input(policy_id: i64) -> serde_json::Value {
        serde_json::json!({
            "kind": "movie",
            "audience": "archive",
            "path": "/mnt/media/movies/archive",
            "policy_id": policy_id,
        })
    }

    async fn first_policy_ids(base: &str) -> Vec<i64> {
        let policies: Vec<serde_json::Value> = reqwest::get(format!("{base}/api/policies"))
            .await
            .expect("policies")
            .json()
            .await
            .expect("policies json");
        policies
            .into_iter()
            .map(|policy| policy["id"].as_i64().expect("policy id"))
            .collect()
    }

    #[tokio::test]
    async fn a_root_round_trips_through_create_and_update() {
        let (_dir, base) = application().await;
        let policy_ids = first_policy_ids(&base).await;
        let roots: Vec<serde_json::Value> = reqwest::get(format!("{base}/api/roots"))
            .await
            .expect("roots")
            .json()
            .await
            .expect("roots json");

        // the schema only knows movie and tv, main and kids
        let rejected = reqwest::Client::new()
            .post(format!("{base}/api/roots"))
            .json(&root_input(policy_ids[0]))
            .send()
            .await
            .expect("create root");
        assert_eq!(rejected.status(), StatusCode::UNPROCESSABLE_ENTITY);

        // (movie, kids) is taken by a seeded root, so free the pair first
        let kids_root = roots[1]["id"].as_i64().expect("movie kids root id");
        let freed = reqwest::Client::new()
            .delete(format!("{base}/api/roots/{kids_root}"))
            .send()
            .await
            .expect("free the seeded movie kids root");
        assert_eq!(freed.status(), StatusCode::NO_CONTENT);

        let mut payload = root_input(policy_ids[0]);
        payload["audience"] = serde_json::json!("kids");
        payload["path"] = serde_json::json!("/mnt/media/movies/archive");
        let created: serde_json::Value = reqwest::Client::new()
            .post(format!("{base}/api/roots"))
            .json(&payload)
            .send()
            .await
            .expect("create root")
            .json()
            .await
            .expect("created json");
        assert_eq!(created["audience"], "kids");
        assert_eq!(created["policy_name"], "Movies — main");
        let id = created["id"].as_i64().expect("id");

        payload["path"] = serde_json::json!("/mnt/media/movies/archive-4k");
        payload["policy_id"] = policy_ids[1].into();
        let updated: serde_json::Value = reqwest::Client::new()
            .put(format!("{base}/api/roots/{id}"))
            .json(&payload)
            .send()
            .await
            .expect("update root")
            .json()
            .await
            .expect("updated json");
        assert_eq!(updated["path"], "/mnt/media/movies/archive-4k");
        assert_eq!(updated["policy_name"], "Movies — kids");

        let deleted = reqwest::Client::new()
            .delete(format!("{base}/api/roots/{id}"))
            .send()
            .await
            .expect("delete root");
        assert_eq!(deleted.status(), StatusCode::NO_CONTENT);
        assert_eq!(
            reqwest::get(format!("{base}/api/roots/{id}"))
                .await
                .expect("get deleted")
                .status(),
            StatusCode::NOT_FOUND
        );
    }

    #[tokio::test]
    async fn an_unknown_kind_or_policy_is_a_422_naming_the_field() {
        let (_dir, base) = application().await;
        let policy_ids = first_policy_ids(&base).await;

        for (mut payload, field) in [
            (root_input(999), "policy_id"),
            (root_input(policy_ids[0]), "kind"),
        ] {
            payload["audience"] = serde_json::json!("main");
            if field == "kind" {
                payload["kind"] = serde_json::json!("book");
                payload["path"] = serde_json::json!("/mnt/media/movies/elsewhere");
            }
            let response = reqwest::Client::new()
                .post(format!("{base}/api/roots"))
                .json(&payload)
                .send()
                .await
                .expect("create root");
            assert_eq!(response.status(), StatusCode::UNPROCESSABLE_ENTITY);
            let body: serde_json::Value = response.json().await.expect("error body");
            assert!(
                body["error"].as_str().expect("text").starts_with(field),
                "{field}: {body}"
            );
        }
    }

    #[tokio::test]
    async fn a_duplicate_path_or_pair_conflicts() {
        let (_dir, base) = application().await;
        let mut path = root_input(1);
        path["audience"] = serde_json::json!("kids");
        path["path"] = serde_json::json!("/mnt/media/movies/kids");
        let response = reqwest::Client::new()
            .post(format!("{base}/api/roots"))
            .json(&path)
            .send()
            .await
            .expect("duplicate path create");
        assert_eq!(response.status(), StatusCode::CONFLICT);

        let mut pair = root_input(1);
        pair["audience"] = serde_json::json!("main");
        pair["path"] = serde_json::json!("/mnt/media/movies/somewhere-new");
        let response = reqwest::Client::new()
            .post(format!("{base}/api/roots"))
            .json(&pair)
            .send()
            .await
            .expect("duplicate pair create");
        assert_eq!(response.status(), StatusCode::CONFLICT);
    }

    #[tokio::test]
    async fn a_root_with_titles_refuses_to_die() {
        let (_dir, base) = application().await;
        let roots: Vec<serde_json::Value> = reqwest::get(format!("{base}/api/roots"))
            .await
            .expect("roots")
            .json()
            .await
            .expect("roots json");
        let main_root = roots[0]["id"].as_i64().expect("root id");

        let created = reqwest::Client::new()
            .post(format!("{base}/api/movies"))
            .json(&serde_json::json!({
                "tmdb_id": 693_134, "title": "Dune Part Two", "year": 2024,
                "original_language": "en", "root_id": main_root,
            }))
            .send()
            .await
            .expect("create movie");
        assert_eq!(created.status(), StatusCode::CREATED);

        let response = reqwest::Client::new()
            .delete(format!("{base}/api/roots/{main_root}"))
            .send()
            .await
            .expect("delete occupied root");
        assert_eq!(response.status(), StatusCode::CONFLICT);
        let body: serde_json::Value = response.json().await.expect("error body");
        assert!(
            body["error"].as_str().expect("text").contains("movie"),
            "{body}"
        );

        // an empty root deletes fine
        let empty_root = roots[3]["id"].as_i64().expect("tv kids root id");
        let response = reqwest::Client::new()
            .delete(format!("{base}/api/roots/{empty_root}"))
            .send()
            .await
            .expect("delete empty root");
        assert_eq!(response.status(), StatusCode::NO_CONTENT);
    }
}