package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"sync"
)

// FilesMap is a struct for listing files by Size and Hash to search for duplicates
type FilesMap struct {
	FilesBySize map[int64]string

	FilesByHash map[string][]string

	FilesHashing chan fileEntry

	FilesIncoming chan fileEntry

	FilesHashed chan fileEntry

	lock sync.Mutex
}

func newFilesMap() *FilesMap {
	return &FilesMap{
		FilesBySize:   map[int64]string{},
		FilesByHash:   map[string][]string{},
		FilesHashed:   make(chan fileEntry),
		FilesIncoming: make(chan fileEntry),
		FilesHashing:  make(chan fileEntry),
	}
}

func (fm *FilesMap) IncomingWorker() {
	for file := range fm.FilesIncoming {
		if *verbose {
			fmt.Println("Incoming", file.path)
		}

		prevFile, ok := fm.FilesBySize[file.size]
		if !ok {
			fm.FilesBySize[file.size] = file.path
			continue
		}

		if prevFile != "" {
			fm.FilesHashing <- fileEntry{prevFile, file.size, ""}
		}

		fm.FilesBySize[file.size] = ""

		fm.FilesHashing <- file
	}
	close(fm.FilesHashing)
}

func (fm *FilesMap) HashingWorker(wg *sync.WaitGroup) {
	for file := range fm.FilesHashing {
		if *verbose {
			fmt.Println("Hashing", file.path)
		}

		hash, err := calculateHash(file.path)

		if err != nil {
			log.Printf("Error calculating Hash for %s: %v\n", file, err)
			continue
		}

		file.hash = hash
		fm.FilesHashed <- file
	}
	wg.Done()
}

func (fm *FilesMap) HashedWorker(done chan bool) {
	for file := range fm.FilesHashed {
		if *verbose {
			fmt.Println("Finishing", file.path)
		}

		fm.lock.Lock()
		if _, ok := fm.FilesByHash[file.hash]; ok {
			fm.FilesByHash[file.hash] = append(fm.FilesByHash[file.hash], file.path)
		} else {
			fm.FilesByHash[file.hash] = []string{file.path}
		}
		fm.lock.Unlock()
	}

	done <- true
}

func (fm *FilesMap) WalkDirectories() {
	for _, path := range flag.Args() {
		filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
			if info.IsDir() {
				return nil
			}

			fm.FilesIncoming <- fileEntry{path, info.Size(), ""}
			return nil
		})
	}

	close(fm.FilesIncoming)
}