use axum::{
  Json,
  extract::{Multipart, Path, State},
  http::{StatusCode, header},
  response::IntoResponse,
};
use pinakes_core::{model::MediaId, upload};
use tokio_util::io::ReaderStream;
use uuid::Uuid;

use crate::{
  dto::{ManagedStorageStatsResponse, UploadResponse},
  error::{ApiError, ApiResult},
  state::AppState,
};

/// Sanitize a filename for use in Content-Disposition headers.
/// Strips characters that could break header parsing or enable injection.
fn sanitize_content_disposition(filename: &str) -> String {
  let safe: String = filename
    .chars()
    .map(|c| {
      if c == '"' || c == '\\' || c == '\n' || c == '\r' {
        '_'
      } else {
        c
      }
    })
    .collect();
  format!("attachment; filename=\"{safe}\"")
}

/// Upload a file to managed storage
/// POST /api/upload
pub async fn upload_file(
  State(state): State<AppState>,
  mut multipart: Multipart,
) -> ApiResult<Json<UploadResponse>> {
  let managed_storage = state
    .managed_storage
    .as_ref()
    .ok_or_else(|| ApiError::bad_request("Managed storage is not enabled"))?;

  let config = state.config.read().await;
  if !config.managed_storage.enabled {
    return Err(ApiError::bad_request("Managed storage is not enabled"));
  }
  drop(config);

  // Extract file from multipart
  let field = multipart
    .next_field()
    .await
    .map_err(|e| {
      ApiError::bad_request(format!("Failed to read multipart field: {e}"))
    })?
    .ok_or_else(|| ApiError::bad_request("No file provided"))?;

  let original_filename = field
    .file_name()
    .map_or_else(|| "unknown".to_string(), std::string::ToString::to_string);

  let content_type = field.content_type().map_or_else(
    || "application/octet-stream".to_string(),
    std::string::ToString::to_string,
  );

  let data = field.bytes().await.map_err(|e| {
    ApiError::bad_request(format!("Failed to read file data: {e}"))
  })?;

  // Process the upload
  let result = upload::process_upload_bytes(
    &state.storage,
    managed_storage.as_ref(),
    &data,
    &original_filename,
    Some(&content_type),
  )
  .await
  .map_err(|e| ApiError::internal(format!("Upload failed: {e}")))?;

  Ok(Json(result.into()))
}

/// Download a managed file
/// GET /api/media/{id}/download
pub async fn download_file(
  State(state): State<AppState>,
  Path(id): Path<Uuid>,
) -> ApiResult<impl IntoResponse> {
  let media_id = MediaId(id);
  let item = state
    .storage
    .get_media(media_id)
    .await
    .map_err(|e| ApiError::not_found(format!("Media not found: {e}")))?;

  let managed_storage = state
    .managed_storage
    .as_ref()
    .ok_or_else(|| ApiError::bad_request("Managed storage is not enabled"))?;

  // Check if this is a managed file
  if item.storage_mode != pinakes_core::model::StorageMode::Managed {
    // For external files, stream from their original path
    let file = tokio::fs::File::open(&item.path)
      .await
      .map_err(|e| ApiError::not_found(format!("File not found: {e}")))?;

    let stream = ReaderStream::new(file);
    let body = axum::body::Body::from_stream(stream);

    let content_type = item.media_type.mime_type();

    let filename = item.original_filename.unwrap_or(item.file_name);

    return Ok((
      [
        (header::CONTENT_TYPE, content_type),
        (
          header::CONTENT_DISPOSITION,
          sanitize_content_disposition(&filename),
        ),
      ],
      body,
    ));
  }

  // For managed files, stream from content-addressable storage
  let file = managed_storage
    .open(&item.content_hash)
    .await
    .map_err(|e| ApiError::not_found(format!("Blob not found: {e}")))?;

  let stream = ReaderStream::new(file);
  let body = axum::body::Body::from_stream(stream);

  let content_type = item.media_type.mime_type();

  let filename = item.original_filename.unwrap_or(item.file_name);

  Ok((
    [
      (header::CONTENT_TYPE, content_type),
      (
        header::CONTENT_DISPOSITION,
        sanitize_content_disposition(&filename),
      ),
    ],
    body,
  ))
}

/// Migrate an external file to managed storage
/// POST /api/media/{id}/move-to-managed
pub async fn move_to_managed(
  State(state): State<AppState>,
  Path(id): Path<Uuid>,
) -> ApiResult<StatusCode> {
  let managed_storage = state
    .managed_storage
    .as_ref()
    .ok_or_else(|| ApiError::bad_request("Managed storage is not enabled"))?;

  let media_id = MediaId(id);
  upload::migrate_to_managed(
    &state.storage,
    managed_storage.as_ref(),
    media_id,
  )
  .await
  .map_err(|e| ApiError::internal(format!("Migration failed: {e}")))?;

  Ok(StatusCode::NO_CONTENT)
}

/// Get managed storage statistics
/// GET /api/managed/stats
pub async fn managed_stats(
  State(state): State<AppState>,
) -> ApiResult<Json<ManagedStorageStatsResponse>> {
  let stats = state
    .storage
    .managed_storage_stats()
    .await
    .map_err(|e| ApiError::internal(format!("Failed to get stats: {e}")))?;

  Ok(Json(stats.into()))
}