package aiprompts

import (
	"regexp"
	"strings"
)

var (
	reLegacyNameTag = regexp.MustCompile(`(?is)<\s*name\s*>\s*\{?\s*(.*?)\s*\}?\s*<\s*/\s*name\s*>`)
	reLegacyMetaTag = regexp.MustCompile(`(?is)<\s*metaDescription\s*>\s*\{?\s*(.*?)\s*\}?\s*<\s*/\s*metaDescription\s*>`)
	reLegacyDescPH  = regexp.MustCompile(`(?i)\{\s*""?\s*OPIS\s+IZDELKA\s*""?\s*\}`)
	reLegacyNamePH  = regexp.MustCompile(`(?i)\{\s*""?\s*STARO\s+IME\s+IZDELKA\s*""?\s*\}`)
	reDoubledQuotes = regexp.MustCompile(`"{2,}`)
)

// LegacyEnhanceParts holds extracted role content from a combined PHP/A1 category Prompt.
type LegacyEnhanceParts struct {
	TitleRules       string
	DescriptionRules string
	MetaRules        string
	WasLegacy        bool
}

// IsLegacyCombinedEnhancePrompt reports whether prompt looks like the old A1/PHP
// combined name+description(+meta) marketing blob (<name>/<metaDescription>/GPT predloga).
func IsLegacyCombinedEnhancePrompt(prompt string) bool {
	p := strings.TrimSpace(prompt)
	if p == "" {
		return false
	}
	// Require real tag wrappers — not instructional mentions like
	// `do NOT … <name>/<metaDescription> tags` in CategoryEnhanceUserTemplate.
	hasNameTag := reLegacyNameTag.MatchString(p)
	hasMetaTag := reLegacyMetaTag.MatchString(p)
	if hasNameTag && (hasMetaTag || strings.Contains(strings.ToLower(p), "gpt predloga")) {
		return true
	}
	if hasNameTag && (strings.Contains(p, "STARO IME IZDELKA") || strings.Contains(p, "OPIS IZDELKA")) {
		return true
	}
	if strings.Contains(p, "STARO IME IZDELKA") && strings.Contains(p, "OPIS IZDELKA") && strings.Contains(strings.ToLower(p), "gpt predloga") {
		return true
	}
	return false
}

// ParseLegacyCombinedEnhancePrompt extracts title / description / meta instruction
// blobs from a legacy combined prompt. Placeholders are modernized to {{name}} /
// {{description}}. WasLegacy is false when no combined markers are found.
func ParseLegacyCombinedEnhancePrompt(prompt string) LegacyEnhanceParts {
	raw := strings.TrimSpace(prompt)
	out := LegacyEnhanceParts{}
	if raw == "" || !IsLegacyCombinedEnhancePrompt(raw) {
		return out
	}
	out.WasLegacy = true

	if m := reLegacyNameTag.FindStringSubmatch(raw); len(m) == 2 {
		out.TitleRules = cleanLegacyInstruction(m[1])
	}
	if m := reLegacyMetaTag.FindStringSubmatch(raw); len(m) == 2 {
		out.MetaRules = cleanLegacyInstruction(m[1])
	}

	rest := reLegacyNameTag.ReplaceAllString(raw, "")
	rest = reLegacyMetaTag.ReplaceAllString(rest, "")
	if idx := strings.Index(strings.ToLower(rest), "gpt predloga:"); idx >= 0 {
		rest = rest[idx+len("gpt predloga:"):]
	}
	// Drop Slovenian boilerplate intro lines that are not body structure.
	rest = stripLegacyIntroNoise(rest)
	out.DescriptionRules = cleanLegacyInstruction(rest)
	return out
}

// SplitLegacyCombinedEnhancePrompt rewrites a legacy combined name+description(+meta)
// prompt into role sections carrying ONLY the original per-category text — the
// Slovenian naming formula under Title, the HTML body structure under Description,
// the SEO instruction under Meta. No schema/role boilerplate is stored: JSON
// schema, role framing, and {{name}}/{{description}}/{{category}}/{{attrs}}
// product context are all supplied at render time (system template +
// processing.ensureCategoryEnhanceUserContext). Non-legacy input returns "" —
// callers leave the category without an override (company default applies).
func SplitLegacyCombinedEnhancePrompt(prompt string) string {
	parts := ParseLegacyCombinedEnhancePrompt(prompt)
	if !parts.WasLegacy {
		return ""
	}
	return BuildCategoryEnhanceOverlay(parts)
}

// BuildCategoryEnhanceOverlay composes a role-sectioned enhance USER overlay from
// extracted legacy parts — the stored text is exactly the split legacy content,
// matching what a user would type into the Title/Description/Meta prompt areas.
func BuildCategoryEnhanceOverlay(parts LegacyEnhanceParts) string {
	var b strings.Builder
	section := func(start, end, body string) {
		b.WriteString(start)
		b.WriteByte('\n')
		if body = strings.TrimSpace(body); body != "" {
			b.WriteString(body)
			b.WriteByte('\n')
		}
		b.WriteString(end)
		b.WriteString("\n\n")
	}
	section(SectionTitleStart, SectionTitleEnd, parts.TitleRules)
	section(SectionDescriptionStart, SectionDescriptionEnd, parts.DescriptionRules)
	section(SectionMetaStart, SectionMetaEnd, parts.MetaRules)
	return strings.TrimSpace(b.String())
}

func cleanLegacyInstruction(s string) string {
	s = modernizeLegacyPlaceholders(s)
	s = reDoubledQuotes.ReplaceAllString(s, `"`)
	s = strings.ReplaceAll(s, "\r\n", "\n")
	s = strings.TrimSpace(s)
	// Collapse excessive blank lines.
	for strings.Contains(s, "\n\n\n") {
		s = strings.ReplaceAll(s, "\n\n\n", "\n\n")
	}
	return s
}

func modernizeLegacyPlaceholders(prompt string) string {
	prompt = reLegacyDescPH.ReplaceAllString(prompt, "{{description}}")
	prompt = reLegacyNamePH.ReplaceAllString(prompt, "{{name}}")
	return prompt
}

func stripLegacyIntroNoise(s string) string {
	lines := strings.Split(s, "\n")
	out := make([]string, 0, len(lines))
	for _, line := range lines {
		trim := strings.TrimSpace(line)
		lower := strings.ToLower(trim)
		switch {
		case trim == "":
			if len(out) > 0 {
				out = append(out, "")
			}
		case strings.HasPrefix(lower, "ustvari nov opis"),
			strings.HasPrefix(lower, "star_opis_izdelka"),
			strings.HasPrefix(lower, "staro_ime_izdelka"),
			strings.HasPrefix(lower, "uporabi spodnjo gpt"),
			strings.HasPrefix(lower, "sledi tej gpt"):
			continue
		default:
			out = append(out, trim)
		}
	}
	return strings.TrimSpace(strings.Join(out, "\n"))
}