package console

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"sort"
	"strconv"
	"strings"
	"time"

	"git.golem15.com/golem15/sm-faq-plugin/models"
	translate "git.golem15.com/golem15/sm-translate-plugin/models"
	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/bonfire"
	"git.golem15.com/golem15/summercms/modules/lagoon"
	"gorm.io/gorm"
)

// WinterOptions are the inputs of faq:import-winter. File is the output of
// scripts/winter-export.sql: one JSON object per line with id, name, slug,
// locale_code, is_active, description, content (the PHP JSON text or a
// list), created_at and updated_at. Force replaces the FAQs a non-empty table
// holds; DryRun reports without writing.
type WinterOptions struct {
	File   string
	Force  bool
	DryRun bool
}

// WinterReport is what faq:import-winter copied (or would copy on a dry
// run): the number of FAQs and one line per FAQ.
type WinterReport struct {
	FAQs  int
	Lines []string
}

// ImportWinter is faq:import-winter: it copies a WinterCMS site's FAQs into
// golem15_faq_faqs, keeping their ids. Each row's locale is looked up by its
// code among the translate locales; an unknown code aborts the import before
// anything is written. A table that already holds FAQs is refused without
// --force, which replaces them in the same transaction. The id sequence is
// moved past the copied ids.
func ImportWinter(app *backpack.App) bonfire.Command {
	return bonfire.Command{
		Name:        "faq:import-winter",
		Description: "Copy a WinterCMS FAQ export into this application",
		Flags: []bonfire.Flag{
			{Name: "file", Description: "FAQ export (JSON lines from scripts/winter-export.sql)"},
			{Name: "force", Description: "Replace the FAQs the table already holds", Bare: true},
			{Name: "dry-run", Description: "Report what would be copied without writing", Bare: true},
		},
		Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
			opts := WinterOptions{
				File:   flagValue(in, "file"),
				Force:  flagOn(in, "force"),
				DryRun: flagOn(in, "dry-run"),
			}
			db, done, err := lookupDB(ctx, app)
			if err != nil {
				return err
			}
			defer done()
			_, err = ImportWinterFile(ctx, db, opts, out)
			return err
		},
	}
}

// ImportWinterFile runs faq:import-winter against db.
func ImportWinterFile(ctx context.Context, db *gorm.DB, opts WinterOptions, out bonfire.Output) (WinterReport, error) {
	var report WinterReport
	if opts.File == "" {
		return report, errors.New("give --file")
	}
	rows, err := readJSONLines(opts.File)
	if err != nil {
		return report, err
	}
	if len(rows) == 0 {
		out.Info("The export holds no FAQs; nothing to copy (0 FAQs).")
		return report, nil
	}
	db = db.WithContext(ctx)
	locales, err := localeIDs(db)
	if err != nil {
		return report, err
	}
	faqs := make([]models.FAQ, 0, len(rows))
	for i, row := range rows {
		faq, code, err := decodeFAQ(row)
		if err != nil {
			return report, fmt.Errorf("%s row %d: %w", opts.File, i+1, err)
		}
		id, ok := locales[code]
		if !ok {
			return report, fmt.Errorf("FAQ %d '%s': locale '%s' is not a translate locale; add it first (nothing was copied)", faq.ID, faq.Slug, code)
		}
		faq.LocaleID = id
		faqs = append(faqs, faq)
		report.Lines = append(report.Lines, fmt.Sprintf("FAQ %d '%s' (%s): %d questions", faq.ID, faq.Slug, code, len(faq.Items())))
	}
	report.FAQs = len(faqs)
	for _, line := range report.Lines {
		out.Info(line)
	}
	var existing int64
	if err := db.Model(&models.FAQ{}).Count(&existing).Error; err != nil {
		return report, err
	}
	if existing > 0 && !opts.Force {
		msg := fmt.Sprintf("golem15_faq_faqs already holds %d FAQs; rerun with --force to replace them.", existing)
		if !opts.DryRun {
			return report, errors.New(msg)
		}
		out.Warning(msg)
	}
	if opts.DryRun {
		out.Info(fmt.Sprintf("Dry run: %d FAQs would be copied.", report.FAQs))
		out.Info("Dry run complete (no changes made).")
		return report, nil
	}
	err = db.Transaction(func(tx *gorm.DB) error {
		if existing > 0 {
			if err := tx.Exec(`DELETE FROM golem15_faq_faqs`).Error; err != nil {
				return err
			}
		}
		for i := range faqs {
			if err := tx.Create(&faqs[i]).Error; err != nil {
				return fmt.Errorf("FAQ %d: %w", faqs[i].ID, err)
			}
		}
		return tx.Exec(`SELECT setval(pg_get_serial_sequence('golem15_faq_faqs', 'id'), COALESCE(MAX(id), 1), MAX(id) IS NOT NULL) FROM golem15_faq_faqs`).Error
	})
	if err != nil {
		return report, err
	}
	out.Success(fmt.Sprintf("Copied %d FAQs.", report.FAQs))
	return report, nil
}

// localeIDs maps every translate locale code to its id.
func localeIDs(db *gorm.DB) (map[string]uint, error) {
	var locales []translate.Locale
	if err := db.Find(&locales).Error; err != nil {
		return nil, err
	}
	out := make(map[string]uint, len(locales))
	for _, l := range locales {
		out[l.Code] = l.ID
	}
	return out, nil
}

// decodeFAQ reads one exported row and returns the FAQ and its locale code.
func decodeFAQ(row map[string]json.RawMessage) (models.FAQ, string, error) {
	var faq models.FAQ
	id, err := jsonUint(row["id"])
	if err != nil || id == 0 {
		return faq, "", fmt.Errorf("id: want a positive id, got %s", row["id"])
	}
	faq.ID = id
	text := func(key string) (string, error) {
		s, err := jsonText(row[key])
		if err != nil {
			return "", fmt.Errorf("%s: %w", key, err)
		}
		if s == nil || strings.TrimSpace(*s) == "" {
			return "", fmt.Errorf("%s is missing", key)
		}
		return *s, nil
	}
	if faq.Name, err = text("name"); err != nil {
		return faq, "", err
	}
	if faq.Slug, err = text("slug"); err != nil {
		return faq, "", err
	}
	code, err := text("locale_code")
	if err != nil {
		return faq, "", err
	}
	if faq.IsActive, err = jsonBool(row["is_active"], false); err != nil {
		return faq, "", fmt.Errorf("is_active: %w", err)
	}
	if faq.Description, err = jsonText(row["description"]); err != nil {
		return faq, "", fmt.Errorf("description: %w", err)
	}
	content, err := decodeContent(row["content"])
	if err != nil {
		return faq, "", fmt.Errorf("content: %w", err)
	}
	faq.Content = lagoon.Jsonable[models.Content]{Data: content, Valid: content != nil}
	for key, dest := range map[string]**time.Time{"created_at": &faq.CreatedAt, "updated_at": &faq.UpdatedAt} {
		if *dest, err = jsonTime(row[key]); err != nil {
			return faq, "", fmt.Errorf("%s: %w", key, err)
		}
	}
	return faq, code, nil
}

// decodeContent reads the PHP content: a JSON list of rows, the same list as
// JSON text (a TEXT column selected as it is), or an object keyed by row
// number; nil for null.
func decodeContent(raw json.RawMessage) (models.Content, error) {
	raw = bytes.TrimSpace(raw)
	if isNull(raw) {
		return nil, nil
	}
	if raw[0] == '"' {
		var text string
		if err := json.Unmarshal(raw, &text); err != nil {
			return nil, err
		}
		raw = bytes.TrimSpace([]byte(text))
		if isNull(raw) {
			return nil, nil
		}
	}
	var list []map[string]any
	if err := json.Unmarshal(raw, &list); err == nil {
		return list, nil
	}
	var keyed map[string]map[string]any
	if err := json.Unmarshal(raw, &keyed); err != nil {
		return nil, errors.New("want a list of question and answer rows")
	}
	keys := make([]string, 0, len(keyed))
	for k := range keyed {
		keys = append(keys, k)
	}
	sort.Slice(keys, func(i, j int) bool {
		a, errA := strconv.Atoi(keys[i])
		b, errB := strconv.Atoi(keys[j])
		if errA == nil && errB == nil {
			return a < b
		}
		return keys[i] < keys[j]
	})
	out := make(models.Content, 0, len(keys))
	for _, k := range keys {
		out = append(out, keyed[k])
	}
	return out, nil
}