package ingestion

import (
	"os"
	"strings"
)

func ParseMarkdown(path string) (string, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return "", err
	}

	content := string(data)
	content = stripFrontmatter(content)
	content = strings.TrimSpace(content)
	return content, nil
}

func stripFrontmatter(content string) string {
	content = strings.TrimLeft(content, "\n\r\t ")
	if !strings.HasPrefix(content, "---") {
		return content
	}

	rest := content[3:]
	closing := findFMClosing(rest)
	if closing < 0 {
		return content
	}

	return strings.TrimLeft(rest[closing:], "\n\r")
}

func findFMClosing(s string) int {
	i := 0
	for i < len(s) {
		nl := strings.IndexByte(s[i:], '\n')
		if nl < 0 {
			break
		}
		lineStart := i + nl + 1
		if lineStart >= len(s) {
			break
		}
		end := strings.IndexByte(s[lineStart:], '\n')
		line := s[lineStart:]
		if end >= 0 {
			line = s[lineStart : lineStart+end]
		}
		if strings.TrimRight(line, "\r") == "---" {
			return lineStart + len(line)
		}
		i = lineStart + len(line)
	}
	return -1
}