use chrono::{DateTime, Utc};
use serde::Serialize;
use sqlx::PgPool;
use uuid::Uuid;

#[derive(Debug, sqlx::FromRow)]
pub struct Upload {
    pub id: Uuid,
    pub event_id: Uuid,
    pub user_id: Uuid,
    pub original_path: String,
    pub preview_path: Option<String>,
    pub thumbnail_path: Option<String>,
    pub mime_type: String,
    pub original_size_bytes: i64,
    pub caption: Option<String>,
    pub compression_status: String,
    pub created_at: DateTime<Utc>,
    pub deleted_at: Option<DateTime<Utc>>,
}

/// On-disk artifact paths returned by the soft-delete methods so the caller can
/// unlink the files after the DB commit.
#[derive(Debug, sqlx::FromRow)]
pub struct DeletedPaths {
    pub original: String,
    pub preview: Option<String>,
    pub thumbnail: Option<String>,
}

#[derive(Debug, Serialize)]
pub struct UploadDto {
    pub id: Uuid,
    pub user_id: Uuid,
    pub uploader_name: String,
    pub preview_url: Option<String>,
    pub thumbnail_url: Option<String>,
    /// Signed gateway URL for the full-resolution original. Always present.
    pub original_url: Option<String>,
    pub mime_type: String,
    pub caption: Option<String>,
    pub hashtags: Vec<String>,
    pub like_count: i64,
    pub comment_count: i64,
    pub liked_by_me: bool,
    pub created_at: DateTime<Utc>,
}

impl Upload {
    /// Generic over the executor so it can run inside the upload transaction
    /// (`&mut *tx`) alongside the quota-counter reservation, keeping the
    /// byte-counter and the row atomic (no quota leak on a mid-write crash).
    pub async fn create<'e, E>(
        executor: E,
        event_id: Uuid,
        user_id: Uuid,
        original_path: &str,
        mime_type: &str,
        original_size_bytes: i64,
        caption: Option<&str>,
    ) -> Result<Self, sqlx::Error>
    where
        E: sqlx::PgExecutor<'e>,
    {
        sqlx::query_as::<_, Self>(
            "INSERT INTO upload (event_id, user_id, original_path, mime_type, original_size_bytes, caption)
             VALUES ($1, $2, $3, $4, $5, $6)
             RETURNING *",
        )
        .bind(event_id)
        .bind(user_id)
        .bind(original_path)
        .bind(mime_type)
        .bind(original_size_bytes)
        .bind(caption)
        .fetch_one(executor)
        .await
    }

    pub async fn find_by_id(pool: &PgPool, id: Uuid) -> Result<Option<Self>, sqlx::Error> {
        sqlx::query_as::<_, Self>(
            "SELECT * FROM upload WHERE id = $1 AND deleted_at IS NULL",
        )
        .bind(id)
        .fetch_optional(pool)
        .await
    }

    /// Event-scoped lookup used by host endpoints so a host of event A cannot
    /// reach uploads belonging to event B.
    pub async fn find_by_id_and_event(
        pool: &PgPool,
        id: Uuid,
        event_id: Uuid,
    ) -> Result<Option<Self>, sqlx::Error> {
        sqlx::query_as::<_, Self>(
            "SELECT * FROM upload
             WHERE id = $1 AND event_id = $2 AND deleted_at IS NULL",
        )
        .bind(id)
        .bind(event_id)
        .fetch_optional(pool)
        .await
    }

    pub async fn set_preview_path(
        pool: &PgPool,
        id: Uuid,
        preview_path: &str,
    ) -> Result<(), sqlx::Error> {
        sqlx::query("UPDATE upload SET preview_path = $2 WHERE id = $1")
            .bind(id)
            .bind(preview_path)
            .execute(pool)
            .await?;
        Ok(())
    }

    pub async fn set_thumbnail_path(
        pool: &PgPool,
        id: Uuid,
        thumbnail_path: &str,
    ) -> Result<(), sqlx::Error> {
        sqlx::query("UPDATE upload SET thumbnail_path = $2 WHERE id = $1")
            .bind(id)
            .bind(thumbnail_path)
            .execute(pool)
            .await?;
        Ok(())
    }

    /// Soft-deletes the upload and decrements the uploader's `total_upload_bytes`.
    /// Done in a single transaction so a crash between the two writes can't leave
    /// the quota counter pointing at bytes the user has already deleted (which would
    /// silently lock them out of future uploads).
    ///
    /// No-op if the row is already deleted — protects against a double-tap on the
    /// delete action double-decrementing the counter.
    ///
    /// Returns the artifact paths of the row that was deleted (`None` if nothing
    /// matched) so the caller can unlink the files after the commit.
    pub async fn soft_delete(pool: &PgPool, id: Uuid) -> Result<Option<DeletedPaths>, sqlx::Error> {
        let mut tx = pool.begin().await?;
        let row: Option<(Uuid, i64, String, Option<String>, Option<String>)> = sqlx::query_as(
            "UPDATE upload
             SET deleted_at = NOW()
             WHERE id = $1 AND deleted_at IS NULL
             RETURNING user_id, original_size_bytes, original_path, preview_path, thumbnail_path",
        )
        .bind(id)
        .fetch_optional(&mut *tx)
        .await?;
        let paths = if let Some((user_id, bytes, original, preview, thumbnail)) = row {
            sqlx::query(
                "UPDATE \"user\"
                 SET total_upload_bytes = GREATEST(0, total_upload_bytes - $2)
                 WHERE id = $1",
            )
            .bind(user_id)
            .bind(bytes)
            .execute(&mut *tx)
            .await?;
            Some(DeletedPaths { original, preview, thumbnail })
        } else {
            None
        };
        tx.commit().await?;
        Ok(paths)
    }

    /// Event-scoped variant of [`Self::soft_delete`]. Returns `None` if no row
    /// matched (already deleted, wrong event, or unknown id) so host handlers
    /// can return a clean 404, and the artifact paths otherwise.
    pub async fn soft_delete_in_event(
        pool: &PgPool,
        id: Uuid,
        event_id: Uuid,
    ) -> Result<Option<DeletedPaths>, sqlx::Error> {
        let mut tx = pool.begin().await?;
        let row: Option<(Uuid, i64, String, Option<String>, Option<String>)> = sqlx::query_as(
            "UPDATE upload
             SET deleted_at = NOW()
             WHERE id = $1 AND event_id = $2 AND deleted_at IS NULL
             RETURNING user_id, original_size_bytes, original_path, preview_path, thumbnail_path",
        )
        .bind(id)
        .bind(event_id)
        .fetch_optional(&mut *tx)
        .await?;
        let paths = if let Some((user_id, bytes, original, preview, thumbnail)) = row {
            sqlx::query(
                "UPDATE \"user\"
                 SET total_upload_bytes = GREATEST(0, total_upload_bytes - $2)
                 WHERE id = $1",
            )
            .bind(user_id)
            .bind(bytes)
            .execute(&mut *tx)
            .await?;
            Some(DeletedPaths { original, preview, thumbnail })
        } else {
            None
        };
        tx.commit().await?;
        Ok(paths)
    }

    pub async fn update_caption(
        pool: &PgPool,
        id: Uuid,
        caption: Option<&str>,
    ) -> Result<(), sqlx::Error> {
        sqlx::query("UPDATE upload SET caption = $2 WHERE id = $1")
            .bind(id)
            .bind(caption)
            .execute(pool)
            .await?;
        Ok(())
    }

    pub async fn set_compression_status(
        pool: &PgPool,
        id: Uuid,
        status: &str,
    ) -> Result<(), sqlx::Error> {
        sqlx::query("UPDATE upload SET compression_status = $2 WHERE id = $1")
            .bind(id)
            .bind(status)
            .execute(pool)
            .await?;
        Ok(())
    }
}