use axum::extract::{Path, Query, State};
use export::rest::AppResponseData;
use jwt::Session;
use serde::Deserialize;

use crate::errors::{ApiError, GitApiError};
use crate::handler;
use crate::service::GitService;
use crate::service::diffs::DiffOptionsDto;
use crate::share::errors::GitError;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize, utoipa::ToSchema)]
#[serde(rename_all = "lowercase")]
pub enum DiffView {
    Shortstat,
    Numstat,
    Files,
    Tree,
}

#[derive(Debug, Clone, Deserialize, utoipa::IntoParams)]
pub struct GetDiffQuery {
    pub base: String,
    pub head: String,
    #[serde(default = "default_view")]
    pub view: DiffView,
    #[serde(default)]
    pub use_merge_base: bool,
}

fn default_view() -> DiffView {
    DiffView::Numstat
}

fn json_err(e: serde_json::Error) -> ApiError {
    GitApiError::from(GitError::Internal(e.to_string())).into()
}

#[utoipa::path(
    get,
    path = "/repos/{space_name}/{repo_name}/diff",
    tag = "diffs",
    description = "按 numstat、shortstat、files 或 tree 视图返回两个修订间的差异。",
    params(
        crate::handler::RepoPath,
        GetDiffQuery,
    ),
    responses(
        (status = 200, description = "diff payload shaped by view (shortstat | numstat | files | tree)", body = AppResponseData<serde_json::Value>)
    )
)]
pub async fn get_diff(
    State(service): State<GitService>,
    session: Session,
    Path(path): Path<crate::handler::RepoPath>,
    Query(q): Query<GetDiffQuery>,
) -> Result<AppResponseData<serde_json::Value>, ApiError> {
    let _ = handler::resolve_reader(
        &service,
        &session,
        path.space_name.clone(),
        path.repo_name.clone(),
    )
    .await?;
    let out = match q.view {
        DiffView::Shortstat => {
            let s = service
                .diff_short_stat(path.space_name, path.repo_name, q.base, q.head)
                .await
                .map_err(GitApiError::from)?;
            serde_json::to_value(s).map_err(json_err)?
        }
        DiffView::Numstat => {
            let s = service
                .diff_stats(
                    path.space_name,
                    path.repo_name,
                    q.base,
                    q.head,
                    DiffOptionsDto::default(),
                )
                .await
                .map_err(GitApiError::from)?;
            serde_json::to_value(s).map_err(json_err)?
        }
        DiffView::Files => {
            let f = service
                .diff_files_changed_between(path.space_name, path.repo_name, q.base, q.head)
                .await
                .map_err(GitApiError::from)?;
            serde_json::to_value(f).map_err(json_err)?
        }
        DiffView::Tree => {
            let t = service
                .diff_tree(
                    path.space_name,
                    path.repo_name,
                    q.base,
                    q.head,
                    q.use_merge_base,
                )
                .await
                .map_err(GitApiError::from)?;
            serde_json::to_value(t).map_err(json_err)?
        }
    };
    Ok(AppResponseData::ok(out))
}