package main

import (
	"fmt"
	"strings"
	"time"
)

type Frontmatter struct {
	Title     string
	Tags      []string
	CreatedAt time.Time
}

func setValue(f *Frontmatter, key string, value string) {
	switch strings.ToLower(key) {
	case "title":
		f.Title = value
	case "tags":
		tags := strings.Split(value, ",")
		for _, tag := range tags {
			f.Tags = append(f.Tags, strings.TrimSpace(tag))
		}
	case "timestamp":
		timestamp, err := time.Parse("2-1-2006", value)
		if err != nil {
			fmt.Printf("Invalid timestamp in post '%s': %s\n", f.Title, err)
		} else {
			f.CreatedAt = timestamp
		}
	}
}

// splits a markdown file into content and frontmatter, removing any whitespace from the former.-------
func splitFrontmatter(input string) (content, frontmatter string) {
	// the frontmatter content is the middle part
	splits := strings.SplitN(input, "---\n", 3)

	// no frontmatter
	if len(splits) < 2 {
		return input, ""
	}

	frontmatter = splits[1]
	content = strings.TrimSpace(splits[2]) // trim leading newline

	return content, frontmatter
}

// returns key:value. feed it ONLY the frontmatter. it doesn't matter if it contains "---" or not.
func parseFrontmatter(input string) Frontmatter {
	var frontmatter Frontmatter

	for line := range strings.Lines(input) {
		matches := strings.SplitN(line, ":", 2) // split (but might have a space)

		if len(matches) == 2 {
			key := strings.ToLower(matches[0])
			value := strings.TrimSpace(matches[1])

			setValue(&frontmatter, key, value)
		}
	}

	return frontmatter
}