package growth

import (
	"fmt"
	"slices"
	"strings"
	"time"
)

const officialCalendarSource = "https://calendar.ut.ac.ir/"
const curatedCommercialSource = "CURATED_COMMERCIAL_1405_V1"

var importedMerchantCategories = []string{
	"ارائه دهنده خدمات اینترنت",
	"مراکز آموزشی مجازی",
	"کیف و کفش فروشی",
	"خدمات شبکه‌های کامپیوتری و اینترنت",
	"فروشگاه لوازم آرایشی و بهداشتی",
}

// Catalog1405 returns a defensive copy of the reviewed initial catalog. Dates are
// Gregorian Tehran-local calendar dates and cover the imported 1405 history plus
// the first 90 forecast days after 2026-06-30.
func Catalog1405() []Event {
	events := []Event{
		catalogEvent("nowruz-1405", "نوروز", "2026-03-21", "2026-03-24", "new-year", EventOfficial, []string{"هدیه", "خرید", "سال-نو"}),
		catalogEvent("nature-day-1405", "روز طبیعت", "2026-04-02", "2026-04-02", "leisure", EventOfficial, []string{"تفریح", "خرید"}),
		catalogEvent("teachers-day-1405", "روز معلم", "2026-05-02", "2026-05-02", "appreciation", EventOfficial, []string{"هدیه", "آموزش", "قدردانی"}),
		catalogEvent("khordad-15-1405", "قیام پانزده خرداد", "2026-06-05", "2026-06-05", "official-holiday", EventOfficial, []string{"تعطیل"}),
		catalogEvent("doctors-day-1405", "روز پزشک", "2026-08-23", "2026-08-23", "appreciation", EventOfficial, []string{"هدیه", "قدردانی", "حرفه‌ای"}),
		catalogEvent("back-to-school-1405", "آمادگی بازگشایی مدارس", "2026-09-10", "2026-09-22", "education-season", EventCommercial, []string{"آموزش", "خرید", "مدرسه"}),
	}
	result := make([]Event, len(events))
	for index, event := range events {
		result[index] = event
		result[index].Tags = slices.Clone(event.Tags)
		result[index].Categories = slices.Clone(event.Categories)
	}
	return result
}

func catalogEvent(id, title, start, end, family string, kind EventKind, tags []string) Event {
	source := officialCalendarSource
	if kind == EventCommercial {
		source = curatedCommercialSource
	}
	return Event{ID: id, TitleFA: title, StartDate: mustCatalogDate(start), EndDate: mustCatalogDate(end), Family: family, Tags: slices.Clone(tags), Source: source, Categories: slices.Clone(importedMerchantCategories), Kind: kind}
}

func ValidateCatalog(events []Event) error {
	seen := make(map[string]struct{}, len(events))
	for index, event := range events {
		if strings.TrimSpace(event.ID) == "" || strings.TrimSpace(event.TitleFA) == "" || strings.TrimSpace(event.Family) == "" || strings.TrimSpace(event.Source) == "" {
			return fmt.Errorf("growth catalog event %d is incomplete", index)
		}
		if _, exists := seen[event.ID]; exists {
			return fmt.Errorf("growth catalog contains duplicate id %q", event.ID)
		}
		seen[event.ID] = struct{}{}
		if event.StartDate.IsZero() || event.EndDate.Before(event.StartDate) {
			return fmt.Errorf("growth catalog event %q has invalid date range", event.ID)
		}
		if event.Kind != EventOfficial && event.Kind != EventCommercial {
			return fmt.Errorf("growth catalog event %q has invalid kind", event.ID)
		}
		if len(normalizedSet(event.Tags)) == 0 || len(event.Categories) == 0 {
			return fmt.Errorf("growth catalog event %q lacks tags or supported categories", event.ID)
		}
	}
	return nil
}

func mustCatalogDate(value string) time.Time {
	parsed, err := time.Parse(time.DateOnly, value)
	if err != nil {
		panic("invalid reviewed event catalog date: " + value)
	}
	return parsed
}