//! Share management (milestone 6).
//!
//! Session-authenticated (management; a share token is never enough — see
//! [`SessionUser`]):
//! - `GET    /api/shares`        — list the current user's shares
//! - `POST   /api/shares`        — create a share
//! - `DELETE /api/shares/{id}`   — delete one of the current user's shares
//!
//! Public (no login; resolved by token):
//! - `GET /api/share/{token}`    — resolve a share for the share page

use std::path::Path;
use std::sync::Arc;

use api_types::{CreateShare, Mode, OkResp, ShareInfo};
use axum::Json;
use axum::extract::{Path as AxumPath, State};
use axum::http::StatusCode;

use crate::api::common::{SessionUser, display_name};
use crate::auth;
use crate::db::ShareRow;
use crate::error::{ApiError, AppState};
use crate::fs;

/// Shared JSON shape for a share (list / create / public resolve).
fn share_info(row: &ShareRow, server_root: &Path) -> ShareInfo {
    ShareInfo {
        id: row.id,
        token: row.token.clone(),
        name: display_name(server_root, &row.target),
        is_file: row.is_file,
        writable: row.mode.is_writable(),
        target: row.target.clone(),
        created_at: row.created_at.clone(),
        expires_at: row.expires_at.clone(),
        // The synthetic root id to use in file API calls.
        root_id: row.id,
    }
}

/// GET /api/shares — list the current user's shares.
pub async fn list(
    State(state): State<Arc<AppState>>,
    auth: SessionUser,
) -> Result<Json<Vec<ShareInfo>>, ApiError> {
    let rows = state.db.user_shares(auth.user.id).await;
    Ok(Json(
        rows.iter().map(|r| share_info(r, &state.root)).collect(),
    ))
}

/// POST /api/shares — create a share.
pub async fn create(
    State(state): State<Arc<AppState>>,
    auth: SessionUser,
    Json(body): Json<CreateShare>,
) -> Result<Json<ShareInfo>, ApiError> {
    if body.writable && !state.db.allow_writable_shares().await {
        return Err(ApiError::new(
            StatusCode::FORBIDDEN,
            "writable shares are disabled",
        ));
    }

    let root = auth
        .roots
        .iter()
        .find(|r| r.id == body.root_id)
        .ok_or_else(|| ApiError::new(StatusCode::FORBIDDEN, "no such folder"))?;

    // A share must never grant more than the source root does, otherwise a
    // read-only root could be escalated to a writable share of itself.
    if body.writable && !root.mode.is_writable() {
        return Err(ApiError::new(
            StatusCode::FORBIDDEN,
            "this folder is read-only for you, so it cannot be shared writably",
        ));
    }

    // Resolve the target to a safe absolute path, then re-express it relative
    // to the server root (the stored `target`).
    let server_root = state.root.clone();
    let root_path = root.path.clone();
    let req = body.path.trim().to_string();
    let req = if req.is_empty() { ".".to_string() } else { req };
    let abs = tokio::task::spawn_blocking(move || fs::resolve_path(&server_root, &root_path, &req))
        .await
        .map_err(|_| ApiError::new(StatusCode::INTERNAL_SERVER_ERROR, "internal error"))??;

    let target = abs
        .strip_prefix(&state.root)
        .map(|p| p.to_string_lossy().into_owned())
        .unwrap_or_else(|_| ".".to_string());
    let is_file = abs.is_file();

    let token = auth::share_token();
    let mode = if body.writable { Mode::Rw } else { Mode::Ro };
    let row = state
        .db
        .create_share(
            auth.user.id,
            &token,
            &target,
            is_file,
            mode,
            body.expires_at.as_deref(),
        )
        .await?;

    Ok(Json(share_info(&row, &state.root)))
}

/// DELETE /api/shares/{id} — delete one of the current user's shares.
pub async fn delete(
    State(state): State<Arc<AppState>>,
    auth: SessionUser,
    AxumPath(id): AxumPath<i64>,
) -> Result<Json<OkResp>, ApiError> {
    if !state.db.delete_share(id, auth.user.id).await {
        return Err(ApiError::new(StatusCode::NOT_FOUND, "share not found"));
    }
    Ok(Json(OkResp { ok: true }))
}

/// GET /api/share/{token} — public resolve for the share page.
pub async fn resolve(
    State(state): State<Arc<AppState>>,
    AxumPath(token): AxumPath<String>,
) -> Result<Json<ShareInfo>, ApiError> {
    let Some(row) = state.db.share_by_token(&token).await else {
        return Err(ApiError::new(StatusCode::NOT_FOUND, "share not found"));
    };
    if row.is_expired() {
        return Err(ApiError::new(StatusCode::GONE, "this share has expired"));
    }
    Ok(Json(share_info(&row, &state.root)))
}