package main

// TODO: read a file line by line

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

type heading struct {
	text   string
	level  int
	line   int
	parent *heading
}

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 count_levels(headings []heading) [6]int {
	level_count := [6]int{}

	for index, _ := range headings {
		switch headings[index].level {
		case 1:
			level_count[0]++
		case 2:
			level_count[1]++
		case 3:
			level_count[2]++
		case 4:
			level_count[3]++
		case 5:
			level_count[4]++
		case 6:
			level_count[5]++
		}
	}

	return level_count
}

func get_parents(headings []heading) {
	for index, _ := range headings {
		if index == 0 {
			headings[index].parent = nil
			continue
		}

		for i := (index - 1); i >= 0; i-- {
			if headings[i].level < headings[index].level {
				headings[index].parent = &headings[i]
				break
			}
		}
	}
}

func print_children(heading *heading, headings []heading) {
	fmt.Printf("pointer of parent: %p\n", heading)

	for index, _ := range headings {
		if headings[index].parent == heading {
			fmt.Printf("Header of parent %p: %s\n", heading, headings[index].text)
		}
	}
}

func print_children_recursive(heading *heading, headings []heading) {
	for index, _ := range headings {
		if headings[index].parent == heading {
			fmt.Printf("Child of parent %p: %s (%p)\n", heading, headings[index].text, &headings[index])
			print_children_recursive(&headings[index], headings)
		}
	}
}

func parse_file(file_name string) []heading {
	file_content_raw, err := os.ReadFile(file_name)

	var headings []heading

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

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

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

func main() {
	file_name := os.Args[1]

	var headings []heading = nil

	headings = parse_file(file_name)

	get_parents(headings)

	print_children_recursive(nil, headings)

	fmt.Printf("%v\n", headings)

	header_level_count := count_levels(headings)

	for i := 0; i < 6; i++ {
		if header_level_count[i] != 0 {
			fmt.Printf("Header %d occurs %d times.\n", (i + 1), header_level_count[i])
		}
	}

	my_children := get_child_indices(0, headings)
	fmt.Printf("%v\n", my_children)
}