package library

import (
	"database/sql"
	"path"
	"strconv"
	"velvettear/badger/internal/config"
	"velvettear/badger/internal/database"
	"velvettear/badger/internal/database/models"
	"velvettear/badger/internal/log"
	"velvettear/badger/internal/metadata"
	"velvettear/badger/internal/tools"
)

// exported function(s)
func FindDuplicates() {
	timestamp := tools.LogTimestamp()
	var duplicates []Duplicate
	rows, error := database.Connection().Model(&models.Track{}).Select("id", "path", "fingerprint", "bitrate").Rows()
	if error != nil {
		log.Error("encountered an error selecting all tracks as rows", error.Error())
		return
	}
	defer rows.Close()
	formatMismatch := config.DuplicatesFormatMismatch()
	var comparisonObjects []comparisonObject
	for rows.Next() {
		comparisonObject, error := toComparisonObject(rows)
		if error != nil {
			continue
		}
		comparisonObjects = append(comparisonObjects, comparisonObject)
	}
	waitChannel := make(chan struct{}, config.Concurrency())
	var objectFormat string
	var duplicateIndices []int
	done := 0
	objectCount := len(comparisonObjects)
	log.Info("comparing "+strconv.Itoa(objectCount)+" audio fingerprints for duplicates...", "concurrency: "+strconv.Itoa(config.Concurrency()))
	for objectCount > 0 {
		object := comparisonObjects[0]
		comparisonObjects = comparisonObjects[1:]
		if formatMismatch {
			objectFormat = path.Ext(object.path)
		}
		waitChannel <- struct{}{}
		go func(object comparisonObject) {
			tmpTimestamp := tools.LogTimestamp()
			for index, comparisonObject := range comparisonObjects {
				if formatMismatch && objectFormat == path.Ext(comparisonObject.path) {
					continue
				}
				duplicate := getDuplicate(&object, &comparisonObject)
				if !duplicate.isValid() {
					continue
				}
				log.Debug("duplicate track detected", "id '"+strconv.Itoa(duplicate.id)+"', good file: "+duplicate.good+", bad file: "+duplicate.bad+", score: "+strconv.FormatFloat(duplicate.score, 'f', 2, 64))
				duplicates = append(duplicates, duplicate)
				if duplicate.id == object.id {
					break
				}
				duplicateIndices = append(duplicateIndices, index)
			}
			done++
			objectCount := len(comparisonObjects)
			log.DebugTimed("finished comparison of the audio fingerprint for track (id: '"+strconv.Itoa(object.id)+"')", tmpTimestamp, strconv.Itoa(done)+"/"+strconv.Itoa(objectCount))
			<-waitChannel
		}(object)
		comparisonObjects = filterDuplicates(comparisonObjects, duplicateIndices)
		duplicateIndices = nil
	}
	log.InfoTimed("found "+strconv.Itoa(len(duplicates))+" duplicates", timestamp)
}

func filterDuplicates(objects []comparisonObject, duplicateIndices []int) []comparisonObject {
	if len(objects) == 0 || len(duplicateIndices) == 0 {
		return objects
	}
	timestamp := tools.LogTimestamp()
	removed := 0
	var tmp []comparisonObject
	for index, object := range objects {
		copyObject := true
		for _, value := range duplicateIndices {
			if index == value {
				copyObject = false
				break
			}
		}
		if !copyObject {
			removed++
			continue
		}
		tmp = append(tmp, object)
	}
	log.DebugTimed("filtered "+strconv.Itoa(removed)+" duplicate track(s) from list", timestamp)
	return tmp
}

func toComparisonObject(row *sql.Rows) (comparisonObject, error) {
	var comparisonObject comparisonObject
	var tmp string
	row.Scan(&comparisonObject.id, &comparisonObject.path, &tmp, &comparisonObject.bitrate)
	fingerprint, error := metadata.FingerprintFromString(tmp)
	if error != nil {
		log.Error("encountered an error parsing the audio fingerprint for file '" + comparisonObject.path + "' from 'string' to '[]int32'")
		return comparisonObject, error
	}
	comparisonObject.fingerprint = fingerprint.Value
	return comparisonObject, nil
}

func getDuplicate(object *comparisonObject, comparisonObject *comparisonObject) Duplicate {
	score := metadata.CompareWith(object.fingerprint, comparisonObject.fingerprint)
	if score < config.DuplicatesFingerprintThreshold() {
		return Duplicate{}
	}
	var duplicate Duplicate
	if object.bitrate > comparisonObject.bitrate {
		duplicate = Duplicate{id: comparisonObject.id, good: object.path, bad: comparisonObject.path}
	} else {
		duplicate = Duplicate{id: object.id, good: comparisonObject.path, bad: object.path}
	}
	duplicate.score = score
	return duplicate
}

func (duplicate *Duplicate) isValid() bool {
	return duplicate.id > 0
}

// struct(s)
type Duplicate struct {
	id    int
	good  string
	bad   string
	score float64
}

type comparisonObject struct {
	id          int
	path        string
	fingerprint []int32
	bitrate     int
}