package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"regexp"
	"strconv"
	"strings"
)

type loadTupContent struct {
	Title    string
	VideoID  string
	Interval float64
	Secs     []float64
	Caps     []string
	Scrsecs  []float64
	Scrcaps  []string
}

func parse_json_floats(part []byte) ([]float64, error) {
	secsStrings := make([]string, 0)
	err := json.Unmarshal(part, &secsStrings)
	if err != nil {
		return nil, err
	}
	ret := make([]float64, 0, len(secsStrings))
	for _, sec := range secsStrings {
		ff, err := strconv.ParseFloat(sec, 64)
		if err != nil {
			return nil, err
		}
		ret = append(ret, ff)
	}
	return ret, nil
}

func NewLoadTupContent(content []byte) (*loadTupContent, error) {

	var err error
	rx := regexp.MustCompile(`videoIdMain = "([^"]+)";var interval = (\d+);var secs  = (.+?);var caps  = (.+?);var scrsecs = (.+?);var scrcaps = (.+?);</script>`)

	parts := rx.FindStringSubmatch(string(content))
	if parts == nil {
		return nil, errors.New("Missing video properties in HTML page")
	}

	if len(parts) != 7 {
		return nil, fmt.Errorf("expected len(parts)=7, got %d", len(parts))
	}

	ltc := loadTupContent{}
	ltc.VideoID = parts[1]
	ltc.Interval, err = strconv.ParseFloat(parts[2], 64)
	if err != nil {
		return nil, err
	}

	ltc.Secs, err = parse_json_floats([]byte(parts[3]))
	if err != nil {
		return nil, err
	}

	err = json.Unmarshal([]byte(parts[4]), &ltc.Caps)
	if err != nil {
		return nil, err
	}

	ltc.Scrsecs, err = parse_json_floats([]byte(parts[5]))
	if err != nil {
		return nil, err
	}

	err = json.Unmarshal([]byte(parts[6]), &ltc.Scrcaps)
	if err != nil {
		return nil, err
	}

	// Parse the page title

	rx = regexp.MustCompile(`(?ms)<h2 style="margin:0 0 0 0;">(.+?)</h2>`)
	parts = rx.FindStringSubmatch(string(content))
	if parts == nil {
		return nil, errors.New("Missing title in HTML page")
	}

	if len(parts) != 2 {
		return nil, fmt.Errorf("expected len(parts)=2, got %d", len(parts))
	}

	ltc.Title = strings.TrimSpace(parts[1])

	return &ltc, nil
}

func (ltc *loadTupContent) Validate() error {
	if len(ltc.Secs) != len(ltc.Caps) {
		return fmt.Errorf("secs/caps length mismatch")
	}

	if len(ltc.Scrsecs) != len(ltc.Scrcaps) {
		return fmt.Errorf("scrsecs/scrcaps length mismatch")
	}

	if !(len(ltc.Scrcaps) == 0 || ltc.Scrcaps[0] == "") {
		return errors.New("unsupported use of strcaps")
	}

	if len(ltc.VideoID) == 0 {
		return errors.New("unexpected blank video ID")
	}

	if ltc.Interval != 100.0 {
		return errors.New("unsupported non-100 duration field")
	}

	return nil
}