// Command seed-bg-intro seeds the Bhagavad-gītā front-matter (Dedication,
// Foreword, Preface, Introduction, The Disciplic Succession) into the
// `prose_chapters` MongoDB collection as intro-segments (book="bg", volume=0).
//
// The segment JSON is produced by extractor/scripts/bg_intro_extract.py.
//
// Usage (from the spsays-bff directory, so .env is picked up):
//
//	go run ./cmd/seed-bg-intro
//	go run ./cmd/seed-bg-intro --dir ../extractor/jsons/books/bg/intro
//
// It is idempotent: existing bg intro-segments are removed before insert.
package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"time"

	"go.uber.org/zap"

	"github.com/prabhupadasays/spsays-bff/internal/config"
	"github.com/prabhupadasays/spsays-bff/internal/repository"
)

type introSegment struct {
	Slug       string   `json:"slug"`
	Title      string   `json:"title"`
	Type       string   `json:"type"`
	Book       string   `json:"book"`
	Volume     int      `json:"volume"`
	Order      int      `json:"order"`
	Paragraphs []string `json:"paragraphs"`
}

func main() {
	dir := flag.String("dir", "../extractor/jsons/books/bg/intro",
		"directory containing bg intro-segment JSON files")
	flag.Parse()

	cfg, err := config.Load()
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to load config: %v\n", err)
		os.Exit(1)
	}

	logger, _ := zap.NewDevelopment()
	defer logger.Sync()
	sugar := logger.Sugar()

	mongoDB, err := repository.NewMongoDB(cfg.MongoURI, cfg.MongoDB, logger)
	if err != nil {
		sugar.Fatalf("failed to connect to MongoDB: %v", err)
	}
	defer mongoDB.Close()

	entries, err := os.ReadDir(*dir)
	if err != nil {
		sugar.Fatalf("failed to read dir %s: %v", *dir, err)
	}

	var segments []introSegment
	var files []string
	for _, e := range entries {
		if e.IsDir() || filepath.Ext(e.Name()) != ".json" {
			continue
		}
		files = append(files, e.Name())
	}
	sort.Strings(files)

	for _, name := range files {
		raw, err := os.ReadFile(filepath.Join(*dir, name))
		if err != nil {
			sugar.Fatalf("read %s: %v", name, err)
		}
		var seg introSegment
		if err := json.Unmarshal(raw, &seg); err != nil {
			sugar.Fatalf("parse %s: %v", name, err)
		}
		if seg.Book != "bg" || seg.Type != "intro-segment" {
			sugar.Warnf("skipping %s (book=%q type=%q)", name, seg.Book, seg.Type)
			continue
		}
		segments = append(segments, seg)
	}

	if len(segments) == 0 {
		sugar.Fatal("no bg intro-segments found to seed")
	}

	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	col := mongoDB.Collection("prose_chapters")

	// Idempotent: clear any previously seeded bg intro-segments.
	del, err := col.DeleteMany(ctx, map[string]any{
		"book": "bg",
		"type": "intro-segment",
	})
	if err != nil {
		sugar.Fatalf("delete existing bg intro-segments: %v", err)
	}
	sugar.Infof("removed %d existing bg intro-segment(s)", del.DeletedCount)

	docs := make([]any, 0, len(segments))
	for _, seg := range segments {
		// chapter is intentionally null for intro-segments (matches the
		// ProseChapterDoc shape used by KB/NoD front matter).
		docs = append(docs, map[string]any{
			"book":       "bg",
			"volume":     0,
			"chapter":    nil,
			"title":      seg.Title,
			"type":       "intro-segment",
			"slug":       seg.Slug,
			"order":      seg.Order,
			"paragraphs": seg.Paragraphs,
		})
		sugar.Infof("  %s (order %d, %d paragraphs)", seg.Slug, seg.Order, len(seg.Paragraphs))
	}

	res, err := col.InsertMany(ctx, docs)
	if err != nil {
		sugar.Fatalf("insert bg intro-segments: %v", err)
	}
	sugar.Infof("inserted %d bg intro-segment(s)", len(res.InsertedIDs))
}