package logic

import (
	"fmt"
	"regexp"
	"strings"

	"img_infinite_canvas/internal/domain/design"
)

var (
	promptReferenceDirectivePattern = regexp.MustCompile(`(?i)(?:参考图|reference image)\s*\d*\s*(?:[（(][^）)\n]+[）)])?\s*[:：]\s*(?:https?://[^\s\]，。]+|data:image/[^\s\]，。]+|/[^\s\]，。]+)`)
	promptImageTokenPattern         = regexp.MustCompile(`\[@image:#\d+:[^:\]]+:(?:\[[^\]]+\]\((?:[^)]+)\)|[^\]]+)\]`)
)

func validateRequiredPrompt(prompt string, allowEmpty bool) error {
	if allowEmpty {
		return nil
	}
	if hasRequiredPromptText(prompt) {
		return nil
	}
	return fmt.Errorf("%w: prompt is required", design.ErrInvalidInput)
}

func hasRequiredPromptText(prompt string) bool {
	prompt = promptImageTokenPattern.ReplaceAllString(prompt, " ")
	prompt = promptReferenceDirectivePattern.ReplaceAllString(prompt, " ")
	for _, line := range strings.Split(prompt, "\n") {
		line = strings.TrimSpace(strings.ReplaceAll(line, "\u00a0", " "))
		if line == "" || isPromptReferenceDirective(line) {
			continue
		}
		return true
	}
	return false
}

func isPromptReferenceDirective(line string) bool {
	lower := strings.ToLower(line)
	hasURL := strings.Contains(lower, "http://") || strings.Contains(lower, "https://")
	if !hasURL {
		return false
	}
	return strings.HasPrefix(line, "参考图") || strings.HasPrefix(lower, "reference image")
}