use actix_multipart::Multipart;
use actix_web::{HttpResponse, web};
use futures_util::StreamExt;
use serde::Serialize;

use crate::api::response::{ApiErrorResponse, ApiResponse};
use crate::error::AppError;
use crate::service::AppService;
use crate::session::Session;

#[derive(Serialize, utoipa::ToSchema)]
pub struct AvatarData {
    pub avatar_url: String,
    pub storage_key: String,
}

pub async fn parse_avatar_field(
    mut payload: Multipart,
) -> Result<(Vec<u8>, Option<String>, Option<String>), AppError> {
    while let Some(Ok(mut field)) = payload.next().await {
        if field.name() == Some("avatar") {
            let content_type = field.content_type().map(|m| m.to_string());
            let file_name = field
                .content_disposition()
                .and_then(|cd| cd.get_filename().map(|s| s.to_string()));
            let mut data: Vec<u8> = Vec::new();
            while let Some(Ok(chunk)) = field.next().await {
                data.extend_from_slice(&chunk);
            }
            return Ok((data, content_type, file_name));
        }
    }
    Err(AppError::BadRequest(
        "missing 'avatar' field in multipart form".into(),
    ))
}

/// Upload user avatar
///
/// Uploads a new avatar image for the authenticated user.
/// Requires authentication. Accepts multipart/form-data with a single "avatar" field.
///
/// Supported formats: PNG, JPEG, WebP, GIF (max 5MB).
///
/// Effects:
/// - Avatar image is stored in S3-compatible object storage
/// - Previous avatar is deleted from storage
/// - User's avatar URL is updated
///
/// Returns the new avatar URL and storage key.
#[utoipa::path(
    post,
    path = "/api/v1/user/account/avatar",
    tag = "User",
    operation_id = "userUploadAvatar",
    request_body(
        content_type = "multipart/form-data",
        description = "Avatar image file in a multipart form field named 'avatar'."
    ),
    responses(
        (status = 200, description = "Avatar uploaded successfully", body = ApiResponse<AvatarData>),
        (status = 400, description = "Invalid parameters: unsupported file type or image too large", body = ApiErrorResponse),
        (status = 401, description = "Authentication required or session expired", body = ApiErrorResponse),
        (status = 404, description = "User not found", body = ApiErrorResponse),
        (status = 500, description = "Internal server error or S3 storage failure", body = ApiErrorResponse),
    ),
    security(
        ("session_cookie" = [])
    )
)]
pub async fn upload_avatar(
    service: web::Data<AppService>,
    session: Session,
    payload: Multipart,
) -> Result<HttpResponse, AppError> {
    let (data, content_type, file_name) = parse_avatar_field(payload).await?;
    let (avatar_url, storage_key) = service
        .user
        .user_upload_avatar(&session, data, content_type, file_name)
        .await?;
    Ok(HttpResponse::Ok().json(ApiResponse::new(AvatarData {
        avatar_url,
        storage_key,
    })))
}