seriatim/internal/render/markdown.go

package render

import (
	"fmt"
	"math"
	"strings"
)

// MarkdownRenderer renders transcript artifacts as Markdown.
type MarkdownRenderer struct{}

// Render renders the transcript into deterministic Markdown.
func (MarkdownRenderer) Render(transcript Transcript, opts Options) (string, error) {
	var lines []string

	title := strings.TrimSpace(opts.Title)
	if title == "" {
		title = "Transcript"
	}
	lines = append(lines, "# "+escapeMarkdownInline(title), "")

	if opts.IncludeMetadata {
		lines = append(lines,
			fmt.Sprintf("- Application: %s", escapeMarkdownInline(transcript.Metadata.Application)),
			fmt.Sprintf("- Version: %s", escapeMarkdownInline(transcript.Metadata.Version)),
			fmt.Sprintf("- Output schema: %s", escapeMarkdownInline(transcript.Schema)),
			"",
		)
	}

	for _, segment := range transcript.Segments {
		parts := make([]string, 0, 4)
		if opts.IncludeTimestamps {
			parts = append(parts, fmt.Sprintf("[%s–%s]", formatTimestamp(segment.Start), formatTimestamp(segment.End)))
		}
		if opts.IncludeSegmentIDs {
			parts = append(parts, fmt.Sprintf("[#%d]", segment.ID))
		}

		text := escapeMarkdownInline(segment.Text)
		if shouldItalicize(segment.Categories) {
			text = "*" + text + "*"
		}
		parts = append(parts, fmt.Sprintf("**%s:** %s", escapeMarkdownInline(segment.Speaker), text))
		lines = append(lines, strings.Join(parts, " "))
		lines = append(lines, "")
	}

	output := strings.Join(lines, "\n")
	if !strings.HasSuffix(output, "\n") {
		output += "\n"
	}
	return output, nil
}

func escapeMarkdownInline(value string) string {
	replacer := strings.NewReplacer(
		`\`, `\\`,
		"`", "\\`",
		"*", "\\*",
		"_", "\\_",
		"{", "\\{",
		"}", "\\}",
		"[", "\\[",
		"]", "\\]",
		"(", "\\(",
		")", "\\)",
		"#", "\\#",
		"+", "\\+",
		"!", "\\!",
		"|", "\\|",
		"<", "\\<",
		">", "\\>",
	)
	return replacer.Replace(value)
}

func shouldItalicize(categories []string) bool {
	for _, category := range categories {
		switch category {
		case "background", "backchannel", "filler":
			return true
		}
	}
	return false
}

func formatTimestamp(seconds float64) string {
	total := int(math.Round(seconds))
	if total < 0 {
		total = 0
	}
	hours := total / 3600
	minutes := (total % 3600) / 60
	remainder := total % 60
	return fmt.Sprintf("%02d:%02d:%02d", hours, minutes, remainder)
}