package runner

import (
	"regexp"
	"strings"
)

// stripMarkdown removes common markdown syntax from src, returning plain text
// suitable for TTS. Mirrors the helper in the scraper's server package.
func stripMarkdown(src string) string {
	src = regexp.MustCompile(`(?m)^#{1,6}\s+`).ReplaceAllString(src, "")
	src = regexp.MustCompile(`\*{1,3}|_{1,3}`).ReplaceAllString(src, "")
	src = regexp.MustCompile("(?s)```.*?```").ReplaceAllString(src, "")
	src = regexp.MustCompile("`[^`]*`").ReplaceAllString(src, "")
	src = regexp.MustCompile(`\[([^\]]+)\]\([^)]+\)`).ReplaceAllString(src, "$1")
	src = regexp.MustCompile(`!\[[^\]]*\]\([^)]+\)`).ReplaceAllString(src, "")
	src = regexp.MustCompile(`(?m)^>\s?`).ReplaceAllString(src, "")
	src = regexp.MustCompile(`(?m)^[-*_]{3,}\s*$`).ReplaceAllString(src, "")
	src = regexp.MustCompile(`\n{3,}`).ReplaceAllString(src, "\n\n")
	return strings.TrimSpace(src)
}

// chunkText splits text into chunks of at most maxChars characters, breaking
// at sentence boundaries (". ", "! ", "? ", "\n") so that the TTS service
// receives natural prose fragments rather than mid-sentence cuts.
//
// If a single sentence exceeds maxChars it is included as its own chunk —
// never silently truncated.
func chunkText(text string, maxChars int) []string {
	if len(text) <= maxChars {
		return []string{text}
	}

	// Sentence-boundary delimiters — we split AFTER these sequences.
	// Order matters: longer sequences first.
	delimiters := []string{".\n", "!\n", "?\n", ". ", "! ", "? ", "\n\n", "\n"}

	var chunks []string
	remaining := text

	for len(remaining) > 0 {
		if len(remaining) <= maxChars {
			chunks = append(chunks, strings.TrimSpace(remaining))
			break
		}

		// Find the last sentence boundary within the maxChars window.
		window := remaining[:maxChars]
		cutAt := -1
		for _, delim := range delimiters {
			idx := strings.LastIndex(window, delim)
			if idx > 0 && idx+len(delim) > cutAt {
				cutAt = idx + len(delim)
			}
		}

		if cutAt <= 0 {
			// No boundary found — hard-break at maxChars to avoid infinite loop.
			cutAt = maxChars
		}

		chunk := strings.TrimSpace(remaining[:cutAt])
		if chunk != "" {
			chunks = append(chunks, chunk)
		}
		remaining = strings.TrimSpace(remaining[cutAt:])
	}

	return chunks
}