package main

import (
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"time"

	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
)

// PhotoPrism's open-source edition doesn't expose any way to map OIDC
// claims to a per-user BasePath — every newly-registered OIDC user
// lands with `BasePath = ""`, which means PhotoPrism's ACL filter
// shows them nothing (non-admin) or everything (admin). Neither is the
// per-user library scope a homelab admin typically wants.
//
// This reconciler reads a declarative `USER_BASEPATHS` env at sidecar
// startup, formatted as `username:originals-relative-path` pairs
// separated by commas (whitespace tolerated), e.g.:
//
//	USER_BASEPATHS="test:test, alice:family/alice, bob:bob"
//
// For every entry the sidecar:
//  1. Ensures the originals subdirectory exists (so PhotoPrism's path:
//     filter has somewhere to point — empty dirs are fine).
//  2. UPDATEs `photoprism.auth_users.base_path` for the matching user
//     row if the current value differs. Idempotent: rows already
//     matching are skipped, and missing users are no-ops (they'll
//     materialise when they log in via OIDC; the periodic ticker
//     catches them on the next pass).
//
// A 60-second ticker keeps the mapping in lockstep with new OIDC
// registrations without needing a webhook.

func parseUserBasepaths(raw string) map[string]string {
	out := map[string]string{}
	for _, p := range strings.Split(raw, ",") {
		p = strings.TrimSpace(p)
		if p == "" {
			continue
		}
		bits := strings.SplitN(p, ":", 2)
		if len(bits) != 2 {
			continue
		}
		u := strings.TrimSpace(bits[0])
		// Strip any leading/trailing slash so the value lands in
		// auth_users.base_path the same way PhotoPrism's own user-edit
		// UI persists it (relative, no slashes).
		path := strings.Trim(strings.TrimSpace(bits[1]), "/")
		if u == "" || path == "" {
			continue
		}
		out[u] = path
	}
	return out
}

func reconcileUserBasepaths(ppDSN, originalsRoot string, mapping map[string]string) error {
	if len(mapping) == 0 {
		return nil
	}
	if ppDSN == "" {
		return fmt.Errorf("USER_BASEPATHS set but PP_DB_PASSWORD missing — can't reach photoprism schema")
	}
	db, err := gorm.Open(mysql.Open(ppDSN), &gorm.Config{
		Logger: logger.Default.LogMode(logger.Warn),
	})
	if err != nil {
		return fmt.Errorf("open pp db: %w", err)
	}
	if sqlDB, derr := db.DB(); derr == nil {
		defer sqlDB.Close()
	}

	for username, path := range mapping {
		target := filepath.Join(originalsRoot, path)
		if err := os.MkdirAll(target, 0o775); err != nil {
			slog.Warn("user-basepath: mkdir failed", "user", username, "path", target, "err", err)
			// Continue — the DB update is still useful so PhotoPrism's
			// ACL kicks in even if the directory is created later.
		}

		// upload_path rides along with base_path so anything a client app
		// uploads (WebDAV sync apps, PhotoPrism's own UI) lands inside the
		// user's library subtree instead of the shared originals root.
		res := db.Exec(`UPDATE auth_users
			SET base_path = ?, upload_path = ?
			WHERE user_name = ?
			  AND (COALESCE(base_path, '') <> ? OR COALESCE(upload_path, '') <> ?)
			  AND deleted_at IS NULL`,
			path, path, username, path, path)
		if res.Error != nil {
			slog.Error("user-basepath: update failed", "user", username, "err", res.Error)
			continue
		}
		if res.RowsAffected > 0 {
			slog.Info("user-basepath: set", "user", username, "path", path)
		}
	}
	return nil
}

func startUserBasepathReconciler(cfg *Config) {
	if len(cfg.UserBasepaths) == 0 {
		return
	}
	slog.Info("user-basepath: starting reconciler", "entries", len(cfg.UserBasepaths))
	apply := func() {
		if err := reconcileUserBasepaths(cfg.PpDSN, cfg.OriginalsRoot, cfg.UserBasepaths); err != nil {
			slog.Warn("user-basepath: reconciliation error", "err", err)
		}
	}
	apply()
	go func() {
		t := time.NewTicker(60 * time.Second)
		defer t.Stop()
		for range t.C {
			apply()
		}
	}()
}