package main

// TODO: read a file line by line
// use heading struct with
// line content
// line number
// heading level

import (
	"fmt"
	"log"
	"os"
	"strings"
)

type heading struct {
	text  string
	level int
	line  int
}

func is_heading(line string) bool {
	if strings.HasPrefix(line, "#") {
		return true
	} else {
		return false
	}
}

func get_heading_level(heading_text string) int {
	level := 0
	for i := 0; heading_text[i] == '#'; i++ {
		level += 1
	}
	return level
}

func print_toc(headings []heading) {
	tab_count := 0
	for index, _ := range headings {
		if index > 0 {
			prev_level := get_heading_level(headings[index-1].text)
			cur_level := get_heading_level(headings[index].text)

			headings[index].level = cur_level

			if cur_level > prev_level {
				tab_count += (cur_level - prev_level)
			} else if cur_level < prev_level {
				tab_count -= (prev_level - cur_level)
			}
			for i := 0; i < tab_count; i++ {
				fmt.Printf("\t")
			}
		}
		fmt.Printf("%v\n", headings[index])
	}
}

func main() {
	file_content_raw, err := os.ReadFile(os.Args[1])

	var headings []heading = nil

	if err != nil {
		log.Fatal(err)
	}

	var file_content string = string(file_content_raw)

	file_lines := strings.Split(file_content, "\n")

	for index, value := range file_lines {
		if is_heading(value) {
			headings = append(headings, heading{value, 0, (index + 1)})
		}
	}

	print_toc(headings)
}