package mget

import (
	"encoding/json"
	"fmt"
	"os"
	"strings"
	"sync"
	"time"
)

type Redo struct {
	Is206         bool      `json:"is_206"`
	OriginUri     string    `json:"origin_uri"`
	Date          time.Time `json:"date"`
	Filename      string    `json:"filename"`
	ContentLength uint64    `json:"content_length"`
	Range         []Range   `json:"range"`
	rangeUpdated  bool
	lastUpdate    time.Time
	lastTotal     uint64
	speed         float64
	total         uint64
	isRedo        bool
	sync.RWMutex
}

func (r *Redo) CacheTotal() uint64 {
	return r.total
}

func (r *Redo) Total() uint64 {
	var total uint64
	for {
		r.RLock()
		for _, v := range r.Range {
			total += v.Max - v.Min + 1
		}
		r.total = total
		r.RUnlock()
		if r.total > r.ContentLength && r.ContentLength > 0 {
			r.reform()
			continue
		}
		break
	}
	return total
}

func (r *Redo) Update(start, end int) error {
	if start < 0 || end < 0 || start > end {
		return fmt.Errorf("invalid range: %d-%d", start, end)
	}
	r.Lock()
	defer r.Unlock()
	r.rangeUpdated = true
	r.Range = append(r.Range, Range{uint64(start), uint64(end)})
	now := time.Now()
	if now.Sub(r.lastUpdate) >= time.Millisecond*500 {
		var total uint64
		for _, v := range r.Range {
			total += v.Max - v.Min + 1
		}
		r.total = total
		r.speed = float64(total-r.lastTotal) / (float64(now.Sub(r.lastUpdate).Milliseconds()) / 1000.00)
		r.lastTotal = total
		r.lastUpdate = now
	}
	return nil
}

func (r *Redo) Percent() float64 {
	return float64(r.Total()) / float64(r.ContentLength)
}

func (r *Redo) FormatPercent() string {
	return fmt.Sprintf("%.2f%%", r.Percent()*100)
}

func (r *Redo) FormatSpeed(unit string) string {
	switch strings.ToLower(unit) {
	case "kb":
		return fmt.Sprintf("%.2f KB/s", r.speed/1024)
	case "mb":
		return fmt.Sprintf("%.2f MB/s", r.speed/1024/1024)
	case "gb":
		return fmt.Sprintf("%.2f GB/s", r.speed/1024/1024/1024)
	default:
		return fmt.Sprintf("%.2f B/s", r.speed)
	}
}

func (r *Redo) Speed() float64 {
	return r.speed
}

func (r *Redo) Save() error {
	var err error
	err = r.reform()
	if err != nil {
		return err
	}
	if r.Filename != "" {
		data, err := json.Marshal(r)
		if err != nil {
			return err
		}
		r.Lock()
		defer r.Unlock()
		return os.WriteFile(r.Filename+".bgrd", data, 0644)
	}
	return nil
}

func (r *Redo) reform() error {
	r.Lock()
	defer r.Unlock()
	if !r.rangeUpdated {
		return nil
	}
	tmp, err := r.uniformRange(r.Range)
	if err != nil {
		return err
	}
	r.Range = tmp
	return nil
}

func (r *Redo) uniformRange(rg []Range) ([]Range, error) {
	return uniformRange(rg)
}

func (r *Redo) ReverseRange() ([]Range, error) {
	r.reform()
	r.RLock()
	defer r.RUnlock()
	return r.uniformRange(subRange([]Range{{0, r.ContentLength - 1}}, r.Range))
}