package examples

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"strings"
)

type Example struct {
	// headers which lead to this example
	Path []string `json:"path"`
	// after -
	Name string `json:"name"`
	// after :
	Comment string `json:"comment"`
	// content of code fence
	Data string `json:"data"`
}

func ReadFile(file *os.File) ([]Example, error) {
	isCodeBlock := false
	var path []string
	sc := bufio.NewScanner(file)
	var currentDataLines []string
	var examples []Example
	currentExample := Example{}
	lineNum := 0
	for sc.Scan() {
		lineNum += 1
		line := sc.Text()
		// fmt.Printf("%q\n", line)
		if strings.HasPrefix(line, "```") {
			// begin or end of code block
			if isCodeBlock {
				// end
				currentExample.Data = strings.Join(currentDataLines, "\n")
				examples = append(examples, currentExample)
				currentExample = Example{}
				currentDataLines = nil
			}
			// otherwise start, don't do anything
			isCodeBlock = !isCodeBlock
		} else if isCodeBlock {
			currentDataLines = append(currentDataLines, line)
		} else if strings.HasPrefix(line, "#") {
			// header
			pathElem := strings.Trim(line, "# ")
			// replace headers
			count := strings.Count(line, "#")
			path = append(path[0:count-1], pathElem)
		} else if strings.HasPrefix(line, "- ") {
			line = strings.TrimPrefix(line, "- ")
			parts := strings.SplitN(line, ":", 2)
			name := parts[0]
			if !strings.HasPrefix(name, "`") || !strings.HasSuffix(name, "`") {
				return examples, errors.New(
					fmt.Sprintf(
						"bad syntax at line number %d: missing inline code for example name",
						lineNum,
					),
				)
			}
			name = strings.Trim(name, "`")
			comment := strings.Trim(parts[1], " .")
			currentExample.Name = name
			currentExample.Comment = comment

			currentExample.Path = append([]string{}, path...)

			// fmt.Printf("Header: %s\n", line)
			// fmt.Printf(
			// 	" - Name: %s, Comment: %q, Path: %v\n",
			// 	currentExample.Name,
			// 	currentExample.Comment,
			// 	currentExample.Path,
			// )
		}
	}
	if isCodeBlock {
		return examples, errors.New(fmt.Sprintf("code block left open somewhere after %d examples", len(examples)))
	}
	return examples, nil
}