//! Admin API (milestone 7): user management and server settings.
//! All routes require an admin session (via [`AdminUser`]).

use std::sync::Arc;

use api_types::{
    AdminShare, AdminUser, CreateUser, Mode, OkResp, Root, RootInfo, Settings, UpdateUser,
};
use axum::Json;
use axum::extract::{Path as AxumPath, State};
use axum::http::StatusCode;

use crate::api::common::AdminUser as AdminGuard;
use crate::api::common::{
    blocking, display_name, hash_password, validate_account_name, validate_password,
};
use crate::api::shares;
use crate::db::Db;
use crate::error::{ApiError, AppState};
use crate::fs;

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

fn root_info(state: &AppState, r: &crate::db::RootRow) -> RootInfo {
    RootInfo {
        id: r.id,
        name: display_name(state, &r.path),
        path: r.path.clone(),
        mode: r.mode,
    }
}

async fn user_info(
    db: &Db,
    state: &AppState,
    user: &crate::db::User,
) -> Result<AdminUser, ApiError> {
    let roots = db.user_roots(user.id).await?;
    Ok(AdminUser {
        id: user.id,
        name: user.name.clone(),
        is_admin: user.is_admin,
        active: user.active,
        roots: roots.iter().map(|r| root_info(state, r)).collect(),
    })
}

/// Validate each requested root path (must exist, be a directory, and stay
/// inside the server root). Returns the (path, mode) pairs.
///
/// The mode needs no check: `Mode` only deserializes from "rw" or "ro", so a
/// bad value is rejected by the `Json` extractor before this runs.
async fn validate_roots(state: &AppState, roots: &[Root]) -> Result<Vec<(String, Mode)>, ApiError> {
    let mut out = Vec::new();
    for r in roots {
        let path = if r.path.trim().is_empty() {
            ".".to_string()
        } else {
            r.path.trim().to_string()
        };
        let server_root = state.root.clone();
        let (path2, label) = (path.clone(), path.clone());
        // The message is built inside the closure so it carries the
        // `FsError`, not the join failure.
        blocking(move || {
            fs::resolve_root(&server_root, &path2).map_err(|e| {
                ApiError::new(StatusCode::BAD_REQUEST, format!("root path '{label}': {e}"))
            })
        })
        .await?;
        out.push((path, r.mode));
    }
    Ok(out)
}

// ---------------------------------------------------------------------------
// Handlers
// ---------------------------------------------------------------------------

/// GET /api/admin/users — list all users with their roots.
pub async fn list_users(
    State(state): State<Arc<AppState>>,
    _admin: AdminGuard,
) -> Result<Json<Vec<AdminUser>>, ApiError> {
    let out = state
        .db
        .all_users_with_roots()
        .await?
        .into_iter()
        .map(|(u, roots)| AdminUser {
            id: u.id,
            name: u.name,
            is_admin: u.is_admin,
            active: u.active,
            roots: roots.iter().map(|r| root_info(&state, r)).collect(),
        })
        .collect();
    Ok(Json(out))
}

/// POST /api/admin/users — create a user.
pub async fn create_user(
    State(state): State<Arc<AppState>>,
    _admin: AdminGuard,
    Json(body): Json<CreateUser>,
) -> Result<Json<AdminUser>, ApiError> {
    let name = body.name.trim().to_string();
    validate_account_name(&name)?;
    validate_password(&body.password)?;
    if state.db.find_user_by_name(&name).await?.is_some() {
        return Err(ApiError::localized(
            StatusCode::CONFLICT,
            "a user with that name already exists",
            "err_user_exists",
        ));
    }
    let roots = validate_roots(&state, &body.roots).await?;

    let pass_hash = hash_password(&body.password).await?;
    let user = state
        .db
        .create_user(&name, &pass_hash, body.is_admin, &roots)
        .await?;
    Ok(Json(user_info(&state.db, &state, &user).await?))
}

/// PUT /api/admin/users/{id} — update a user (password / is_admin / active /
/// roots; all optional).
pub async fn update_user(
    State(state): State<Arc<AppState>>,
    admin: AdminGuard,
    AxumPath(id): AxumPath<i64>,
    Json(body): Json<UpdateUser>,
) -> Result<Json<AdminUser>, ApiError> {
    let target = state.db.find_user_by_id(id).await?.ok_or_else(|| {
        ApiError::localized(
            StatusCode::NOT_FOUND,
            "user not found",
            "err_user_not_found",
        )
    })?;

    // Lockout guards: an admin cannot demote, disable, or delete themselves.
    if id == admin.user.id {
        if body.is_admin == Some(false) {
            return Err(ApiError::localized(
                StatusCode::BAD_REQUEST,
                "you cannot remove your own admin rights",
                "err_own_admin",
            ));
        }
        if body.active == Some(false) {
            return Err(ApiError::localized(
                StatusCode::BAD_REQUEST,
                "you cannot disable your own account",
                "err_own_account",
            ));
        }
    }
    // Never allow dropping to zero active admins.
    let demoting = id != admin.user.id && body.is_admin == Some(false) && target.is_admin;
    let disabling =
        id != admin.user.id && body.active == Some(false) && target.active && target.is_admin;
    if (demoting || disabling) && state.db.count_admins().await? <= 1 {
        return Err(ApiError::localized(
            StatusCode::BAD_REQUEST,
            "cannot remove the last active admin",
            "err_last_admin",
        ));
    }

    let hash = match &body.password {
        Some(pw) => {
            validate_password(pw)?;
            Some(hash_password(pw).await?)
        }
        None => None,
    };
    let pairs = match &body.roots {
        Some(roots) => Some(validate_roots(&state, roots).await?),
        None => None,
    };
    state
        .db
        .update_user(
            id,
            hash.as_deref(),
            body.is_admin,
            body.active,
            pairs.as_deref(),
        )
        .await?;
    crate::auth::forget_verified();

    let updated = state.db.find_user_by_id(id).await?.ok_or_else(|| {
        ApiError::localized(
            StatusCode::NOT_FOUND,
            "user not found",
            "err_user_not_found",
        )
    })?;
    Ok(Json(user_info(&state.db, &state, &updated).await?))
}

/// DELETE /api/admin/users/{id} — delete a user (not yourself).
pub async fn delete_user(
    State(state): State<Arc<AppState>>,
    admin: AdminGuard,
    AxumPath(id): AxumPath<i64>,
) -> Result<Json<OkResp>, ApiError> {
    if id == admin.user.id {
        return Err(ApiError::localized(
            StatusCode::BAD_REQUEST,
            "you cannot delete your own account",
            "err_own_delete",
        ));
    }
    let target = state.db.find_user_by_id(id).await?.ok_or_else(|| {
        ApiError::localized(
            StatusCode::NOT_FOUND,
            "user not found",
            "err_user_not_found",
        )
    })?;
    if target.is_admin && target.active && state.db.count_admins().await? <= 1 {
        return Err(ApiError::localized(
            StatusCode::BAD_REQUEST,
            "cannot delete the last active admin",
            "err_last_admin_delete",
        ));
    }
    crate::auth::forget_verified();
    if !state.db.delete_user(id).await? {
        return Err(ApiError::localized(
            StatusCode::NOT_FOUND,
            "user not found",
            "err_user_not_found",
        ));
    }
    Ok(Json(OkResp {}))
}

// ---------------------------------------------------------------------------
// Shares
// ---------------------------------------------------------------------------

/// GET /api/admin/shares — every share on the server with its creator.
///
/// Answers with the full share tokens, which the admin view offers as copy
/// buttons. A token is access, so this route stays admin-only.
pub async fn list_shares(
    State(state): State<Arc<AppState>>,
    _admin: AdminGuard,
) -> Result<Json<Vec<AdminShare>>, ApiError> {
    let rows = state.db.all_shares_with_creators().await?;
    Ok(Json(
        rows.iter()
            .map(|r| AdminShare {
                share: shares::share_info(&r.share, &state),
                creator_id: r.share.creator_id,
                creator_name: r.creator_name.clone(),
                creator_active: r.creator_active,
            })
            .collect(),
    ))
}

/// DELETE /api/admin/shares/{id} — revoke a share whoever created it. The
/// user-facing `DELETE /api/shares/{id}` only touches the caller's own links.
pub async fn delete_share(
    State(state): State<Arc<AppState>>,
    _admin: AdminGuard,
    AxumPath(id): AxumPath<i64>,
) -> Result<Json<OkResp>, ApiError> {
    if !state.db.admin_delete_share(id).await? {
        return Err(ApiError::localized(
            StatusCode::NOT_FOUND,
            "share not found",
            "err_share_not_found",
        ));
    }
    Ok(Json(OkResp {}))
}

/// GET /api/admin/settings
pub async fn get_settings(
    State(state): State<Arc<AppState>>,
    _admin: AdminGuard,
) -> Result<Json<Settings>, ApiError> {
    Ok(Json(Settings {
        allow_writable_shares: state.db.allow_writable_shares().await?,
        search_excludes: state.db.search_excludes().await?,
    }))
}

/// PUT /api/admin/settings
pub async fn update_settings(
    State(state): State<Arc<AppState>>,
    _admin: AdminGuard,
    Json(body): Json<Settings>,
) -> Result<Json<Settings>, ApiError> {
    state
        .db
        .set_allow_writable_shares(body.allow_writable_shares)
        .await?;
    // Normalised so the search can compare plain strings. "." is dropped:
    // excluding the root would switch search off instead of narrowing it.
    let mut excludes: Vec<String> = Vec::new();
    for p in &body.search_excludes {
        let p = p.trim().replace('\\', "/");
        let p = p.trim_matches('/');
        if p.is_empty() || p == "." || excludes.iter().any(|e| e == p) {
            continue;
        }
        excludes.push(p.to_string());
    }
    state.db.set_search_excludes(&excludes).await?;
    Ok(Json(Settings {
        allow_writable_shares: body.allow_writable_shares,
        search_excludes: excludes,
    }))
}