package repository

import (
	"context"
	"encoding/json"
	"errors"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"
)

func revisionPreviewTableExists(ctx context.Context, q queryRower) bool {
	var n int
	err := q.QueryRow(ctx, `
		SELECT 1 FROM information_schema.tables
		WHERE table_schema = 'public' AND table_name = 'config_revision_preview'
		LIMIT 1`).Scan(&n)
	return err == nil
}

type queryRower interface {
	QueryRow(ctx context.Context, sql string, args ...any) pgx.Row
}

func loadRevisionPreview(ctx context.Context, q queryRower, revisionID string, metaPreview map[string]string) map[string]string {
	if revisionPreviewTableExists(ctx, q) {
		var raw []byte
		err := q.QueryRow(ctx, `
			SELECT fragments FROM config_revision_preview WHERE revision_id = $1::uuid`,
			revisionID).Scan(&raw)
		if err == nil {
			out := map[string]string{}
			_ = json.Unmarshal(raw, &out)
			if out == nil {
				out = map[string]string{}
			}
			return out
		}
		if !errors.Is(err, pgx.ErrNoRows) {
			return metaPreview
		}
	}
	if metaPreview == nil {
		return map[string]string{}
	}
	return metaPreview
}

type execQuerier interface {
	queryRower
	Exec(ctx context.Context, sql string, arguments ...any) (pgconn.CommandTag, error)
}

func insertRevisionPreview(ctx context.Context, db execQuerier, revisionID string, preview map[string]string) error {
	if !revisionPreviewTableExists(ctx, db) {
		return nil
	}
	if preview == nil {
		preview = map[string]string{}
	}
	raw, err := json.Marshal(preview)
	if err != nil {
		return err
	}
	_, err = db.Exec(ctx, `
		INSERT INTO config_revision_preview (revision_id, fragments)
		VALUES ($1::uuid, $2::jsonb)
		ON CONFLICT (revision_id) DO UPDATE SET fragments = EXCLUDED.fragments`,
		revisionID, string(raw))
	return err
}

func copyRevisionPreview(ctx context.Context, db execQuerier, dstRevisionID, srcRevisionID string) error {
	if !revisionPreviewTableExists(ctx, db) {
		return nil
	}
	_, err := db.Exec(ctx, `
		INSERT INTO config_revision_preview (revision_id, fragments)
		SELECT $1::uuid, fragments FROM config_revision_preview WHERE revision_id = $2::uuid
		ON CONFLICT (revision_id) DO UPDATE SET fragments = EXCLUDED.fragments`,
		dstRevisionID, srcRevisionID)
	return err
}

func revisionMetaWithoutPreview(materializedPrefixCount int) (string, error) {
	raw, err := json.Marshal(map[string]any{
		"materialized_prefix_count": materializedPrefixCount,
	})
	return string(raw), err
}