package main

import (
	"crypto/sha1"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"regexp"
	"sort"
)

type Storage struct {
	Path string
}

var (
	tokenPattern = regexp.MustCompile(`[a-fA-F0-9]{10,}`)
)

func (s *Storage) MustInit() error {
	os.Mkdir(s.Path, 0755)
	os.Mkdir(s.Path+"/battles", 0755)
	os.Mkdir(s.Path+"/tokens", 0700)
	return nil
}

func (s *Storage) CanPost(token string) (bool, error) {
	if !tokenPattern.MatchString(token) {
		return false, errors.New("invalid token")
	}
	_, err := os.Stat(s.Path + "/tokens/" + token)
	return err == nil, nil
}

func (b *BattleStub) CalculateHash() string {
	hash := sha1.New()
	killmails := b.Killmails
	sort.Slice(killmails, func(lhs, rhs int) bool {
		return killmails[lhs].Id < killmails[rhs].Id
	})
	for _, km := range killmails {
		fmt.Fprint(hash, km.Id)
	}
	sum := hash.Sum(nil)
	return hex.EncodeToString(sum[:])
}

func (b *Battle) From(stub *BattleStub) error {
	if len(stub.Killmails) < 1 {
		return errors.New("missing killmails")
	}
	b.Id = stub.CalculateHash()
	b.Ships = make(map[int32]Ship)
	b.Locations = make(map[int32]Location)
	b.Names = make(map[int32]string)
	mark := func (id int32) { if id != 0 { b.Names[id] = "" } }
	for _, km := range stub.Killmails {
		details, err := GetKillmail(km.Id, km.Hash)
		if err != nil {
			return errors.New("could not retrieve killmail details")
		}
		details.Hash = km.Hash
		b.Locations[details.SolarSystemId] = Location{}
		b.Ships[details.Victim.ShipTypeId] = Ship{}
		mark(details.Victim.CharacterId)
		mark(details.Victim.CorporationId)
		mark(details.Victim.AllianceId)
		mark(details.Victim.FactionId)
		if b.StartTime.IsZero() || b.StartTime.After(details.Time) {
			b.StartTime = details.Time
		}
		if b.EndTime.IsZero() || b.EndTime.Before(details.Time) {
			b.EndTime = details.Time
		}
		b.Killmails = append(b.Killmails, details)
	}
	b.Teams = stub.Teams
	for key := range b.Ships {
		t, err := GetType(key)
		if err != nil {
			return errors.New("could not retrieve type details")
		}
		g, err := GetGroup(t.GroupId)
		if err != nil {
			return errors.New("could not retrieve group details")
		}
		b.Ships[key] = Ship{Name: t.Name, Group: g.Name}
	}
	for key := range b.Locations {
		s, err := GetSolarSystem(key)
		if err != nil {
			return errors.New("could not retrieve solar system details")
		}
		c, err := GetConstellation(s.ConstellationId)
		if err != nil {
			return errors.New("could not retrieve constellation details")
		}
		r, err := GetRegion(c.RegionId)
		if err != nil {
			return errors.New("could not retrieve region details")
		}
		b.Locations[key] = Location{
			Name:          s.Name,
			Security:      s.Security,
			Position:      s.Position,
			Constellation: c.Name,
			Region:        r.Name,
		}
		if b.Name == "" {
			b.Name = fmt.Sprintf("Fight in %s", s.Name)
		} else {
			b.Name = fmt.Sprintf("%s, %s", b.Name, s.Name)
		}
	}
	// TODO: Resolve Names
	return nil
}

func (s *Storage) LoadBattle(battle *Battle) error {
	stream, err := os.Open(s.Path + "/battles/" + battle.Id)
	if err != nil {
		return err
	}
	decoder := json.NewDecoder(stream)
	if err = decoder.Decode(battle); err != nil {
		return err
	}

	return nil
}

func (s *Storage) AddBattle(battle *Battle) error {
	data, err := json.Marshal(battle)
	if err != nil {
		return err
	}
	return ioutil.WriteFile(s.Path+"/battles/"+battle.Id, data, 0644)
}

func (s *Storage) ServeBattle(id string, w http.ResponseWriter, r *http.Request) {
	w.Header().Add("Content-Type", "application/json")
	http.ServeFile(w, r, s.Path+"/battles/"+id)
}

func (s *Storage) ListRecentBattles(count int) ([]Battle, error) {
	files, err := ioutil.ReadDir(s.Path + "/battles")
	if err != nil {
		return nil, err
	}

	sort.Slice(files, func(lhs, rhs int) bool {
		return files[lhs].ModTime().After(files[rhs].ModTime())
	})

	battles := make([]Battle, 0, count)

	for i := 0; i < count && i < len(files); i++ {
		battle := Battle{Id: files[i].Name(), LastModified: files[i].ModTime()}
		if err = s.LoadBattle(&battle); err != nil {
			return nil, err
		}
		battles = append(battles, battle)
	}

	return battles, nil
}