package repository

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/geo-platform/tenant-api/internal/shared/cache"
	"github.com/jackc/pgx/v5"
	"golang.org/x/sync/singleflight"
)

const (
	templateCacheTTL      = 5 * time.Minute
	templateCacheEmptyTTL = 1 * time.Minute
)

type cachedTemplateRepository struct {
	inner TemplateRepository
	cache cache.Cache
	group singleflight.Group
}

func NewCachedTemplateRepository(inner TemplateRepository, c cache.Cache) TemplateRepository {
	return &cachedTemplateRepository{inner: inner, cache: c}
}

func (r *cachedTemplateRepository) ListTemplates(ctx context.Context, tenantID int64) ([]TemplateRecord, error) {
	key := fmt.Sprintf("tmpl_list:%d", tenantID)

	records, _, err := cache.LoadJSONWithEmpty(ctx, r.cache, &r.group, key, templateCacheTTL, templateCacheEmptyTTL, func(loadCtx context.Context) ([]TemplateRecord, bool, error) {
		records, err := r.inner.ListTemplates(loadCtx, tenantID)
		if err != nil {
			return nil, false, err
		}
		return records, true, nil
	})
	if err != nil {
		return nil, err
	}
	for i := range records {
		applyPlatformTemplatePromptOverrides(&records[i])
	}
	return records, nil
}

func (r *cachedTemplateRepository) GetTemplateByID(ctx context.Context, id, tenantID int64) (*TemplateRecord, error) {
	key := fmt.Sprintf("tmpl:%d:%d", tenantID, id)

	record, found, err := cache.LoadJSONWithEmpty(ctx, r.cache, &r.group, key, templateCacheTTL, templateCacheEmptyTTL, func(loadCtx context.Context) (*TemplateRecord, bool, error) {
		record, err := r.inner.GetTemplateByID(loadCtx, id, tenantID)
		if err != nil {
			if errors.Is(err, pgx.ErrNoRows) {
				return nil, false, nil
			}
			return nil, false, err
		}
		return record, true, nil
	})
	if err != nil {
		return nil, err
	}
	if !found || record == nil {
		return nil, pgx.ErrNoRows
	}
	applyPlatformTemplatePromptOverrides(record)
	return record, nil
}