package main

import (
	"encoding/json"
	"fmt"
	"log"
	"math"
	"os"
	"path/filepath"
	"sync"
	"time"

	"srs.epita.fr/fic-server/libfic"
)

var (
	noValidateChallenge bool
)

type Walker struct {
	LastSync     map[string]*TSValue
	LastSyncLock sync.RWMutex
	Exercices    AirbusExercicesBindings
	Teams        map[string]fic.ExportedTeam
	RevTeams     map[string]string
	TeamBindings map[string]*AirbusTeam
	API          AirbusAPI
	Coeff        float64
}

func (w *Walker) fetchTeams() error {
	teams, err := w.API.GetTeams()
	if err != nil {
		return err
	}

	w.RevTeams = map[string]string{}
	w.TeamBindings = map[string]*AirbusTeam{}

	for tid, team := range w.Teams {
		for i, t := range teams {
			if team.Name == t.Name || team.ExternalId == t.Name {
				w.TeamBindings[tid] = &teams[i]
				break
			}
		}

		if _, ok := w.TeamBindings[tid]; !ok {
			log.Printf("Team binding not found: %s - %s", tid, team.Name)
		}

		w.RevTeams[team.Name] = tid
	}

	return nil
}

func (w *Walker) treat(path string) error {
	teamid := filepath.Base(filepath.Dir(path))

	if _, ok := w.TeamBindings[teamid]; ok {
		return w.TreatScoreGrid(path, w.TeamBindings[teamid])
	}

	return nil
}

func (w *Walker) LoadScoreState(path string) (int64, error) {
	mypath := filepath.Join(filepath.Dir(path), "airbus.json")
	if _, err := os.Stat(mypath); os.IsNotExist(err) {
		fd, err := os.Create(mypath)
		if err != nil {
			return 0, err
		}
		defer fd.Close()

		fd.Write([]byte("0"))
		return 0, nil
	}

	fd, err := os.Open(mypath)
	if err != nil {
		return 0, err
	}
	defer fd.Close()

	var ret int64

	jdec := json.NewDecoder(fd)
	if err := jdec.Decode(&ret); err != nil {
		return 0, fmt.Errorf("an error occurs when trying to decode airbus.json: %w", err)
	}

	return ret, nil
}

func (w *Walker) LoadScoreGrid(path string) ([]fic.ScoreGridRow, error) {
	fd, err := os.Open(filepath.Join(filepath.Dir(path), "scores.json"))
	if err != nil {
		return nil, err
	}
	defer fd.Close()

	var ret []fic.ScoreGridRow

	jdec := json.NewDecoder(fd)
	if err := jdec.Decode(&ret); err != nil {
		return nil, fmt.Errorf("an error occurs when trying to decode airbus.json: %w", err)
	}

	return ret, nil
}

func (w *Walker) WalkScoreSync(path string, d os.DirEntry, err error) error {
	if filepath.Base(path) == "scores.json" {
		return w.treat(path)
	}

	return nil
}

func (w *Walker) loadMyFile(path string) (*fic.MyTeam, error) {
	fd, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer fd.Close()

	var ret fic.MyTeam

	jdec := json.NewDecoder(fd)
	if err := jdec.Decode(&ret); err != nil {
		return nil, fmt.Errorf("an error occurs when trying to decode airbus.json: %w", err)
	}

	return &ret, nil
}

func (w *Walker) WalkScore(path string, d os.DirEntry, err error) error {
	if filepath.Base(path) == "scores.json" {
		go w.treat(path)
	}
	return nil
}

func (w *Walker) TreatScoreGrid(path string, airbusTeam *AirbusTeam) error {
	// Read score grid
	fdscores, err := os.Open(path)
	if err != nil {
		return err
	}
	defer fdscores.Close()

	teamscores, err := fic.ReadScoreGrid(fdscores)
	if err != nil {
		return err
	}

	// Found all new entries
	maxts := TSValue{
		Time: time.Time{},
	}
	w.LastSyncLock.RLock()
	ts, ok := w.LastSync[airbusTeam.Name]
	w.LastSyncLock.RUnlock()
	if ok {
		maxts = *ts
	} else {
		ts = &TSValue{Time: time.Time{}}
	}
	var expected_score float64
	for _, row := range teamscores {
		expected_score += row.Points * row.Coeff * w.Coeff
		if row.Time.After(ts.Time) {
			if !noValidateChallenge && row.Reason == "Validation" {
				err = w.API.ValidateChallengeFromUser(airbusTeam, w.Exercices[row.IdExercice])
			} else if row.Reason == "Tries" {
				// Just add 1 try at a time as the field is updated
				row.Points = fic.TermTriesSeq(fic.ReverseTriesPoints(int64(row.Points)))
				err = w.API.AwardUser(airbusTeam, int64(math.Trunc(row.Points*row.Coeff*w.Coeff)), row.Reason)
			} else {
				err = w.API.AwardUser(airbusTeam, int64(row.Points*row.Coeff*w.Coeff), row.Reason)
			}

			if err != nil {
				return err
			}

			maxts.Score += int64(math.Trunc(row.Points * row.Coeff * w.Coeff))
		}
		if row.Time.After(maxts.Time) {
			maxts.Time = row.Time
		}
	}

	if int64(math.Trunc(expected_score)) != maxts.Score {
		log.Printf("Team %q need balancing: expected: %f, saved: %d", airbusTeam.Name, expected_score, maxts.Score)
		err = w.API.AwardUser(airbusTeam, int64(math.Trunc(expected_score))-maxts.Score, "Balancing")
		if err != nil {
			return fmt.Errorf("unable to balance score for %q: %w", airbusTeam.Name, err)
		}
		maxts.Score = int64(math.Trunc(expected_score))
	}

	w.LastSyncLock.Lock()
	w.LastSync[airbusTeam.Name] = &maxts
	w.LastSyncLock.Unlock()

	return nil
}

func (w *Walker) BalanceScores() error {
	for team_id := range w.Teams {
		myteam, err := w.loadMyFile(filepath.Join(TeamsDir, team_id, "my.json"))
		if err != nil {
			return fmt.Errorf("Unable to open %s/my.json: %w", team_id, err)
		}

		airbusTeam := w.TeamBindings[fmt.Sprintf("%d", myteam.Id)]

		expected_score := int64(math.Floor(float64(myteam.Points100) * w.Coeff / 100))
		if airbusTeam == nil {
			log.Printf("Skip team %q (tid=%d): no binding found", myteam.Name, myteam.Id)
		} else if airbusTeam.Score != expected_score {
			err := w.API.AwardUser(airbusTeam, expected_score-airbusTeam.Score, "Balancing")
			if err != nil {
				return fmt.Errorf("Unable to award team %s: %w", myteam.Name, err)
			}

			w.LastSyncLock.Lock()
			if _, ok := w.LastSync[airbusTeam.Name]; !ok {
				w.LastSync[airbusTeam.Name] = &TSValue{}
			}

			w.LastSync[airbusTeam.Name].Score = expected_score
			w.LastSync[airbusTeam.Name].Time = time.Now()
			w.LastSyncLock.Unlock()
		}
	}

	return nil
}