/*
 * Minio Client (C) 2015 Minio, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package main

import (
	"strings"

	"github.com/fatih/color"
	"github.com/minio/cli"
	"github.com/minio/mc/pkg/console"
)

// Compute differences between two files or folders.
var diffCmd = cli.Command{
	Name:        "diff",
	Usage:       "Compute differences between two files or folders.",
	Description: "NOTE: This command *DOES NOT* check for content similarity, which means objects with same size, but different content will not be spotted.",
	Action:      mainDiff,
	CustomHelpTemplate: `NAME:
   mc {{.Name}} - {{.Usage}}

USAGE:
   mc {{.Name}} FIRST SECOND

EXAMPLES:
   1. Compare foo.ogg on a local filesystem with bar.ogg on Amazon AWS cloud storage.
      $ mc {{.Name}} foo.ogg https://s3.amazonaws.com/jukebox/bar.ogg

   2. Compare two different folders on a local filesystem.
      $ mc {{.Name}} ~/Photos /Media/Backup/Photos
`,
}

func checkDiffSyntax(ctx *cli.Context) {
	if len(ctx.Args()) != 2 || ctx.Args().First() == "help" {
		cli.ShowCommandHelpAndExit(ctx, "diff", 1) // last argument is exit code
	}
	for _, arg := range ctx.Args() {
		if strings.TrimSpace(arg) == "" {
			fatalIf(errInvalidArgument().Trace(), "Unable to validate empty argument.")
		}
	}
	if isURLRecursive(ctx.Args().Last()) {
		fatalIf(errInvalidArgument().Trace(), "Second argument ‘"+ctx.Args().Last()+"’ cannot be recursive.")
	}
}

// doDiffMain runs the diff.
func doDiffMain(firstURL, secondURL string, recursive bool) <-chan diffMessage {
	ch := make(chan diffMessage, 10000)
	go doDiffInRoutine(firstURL, secondURL, recursive, ch)
	return ch
}

// doDiffInRoutine run diff in a go-routine sending back messages over all channel.
func doDiffInRoutine(firstURL, secondURL string, recursive bool, ch chan diffMessage) {
	defer close(ch)
	firstClnt, firstContent, err := url2Stat(firstURL)
	if err != nil {
		ch <- diffMessage{
			Error: err.Trace(firstURL),
		}
		return
	}
	secondClnt, secondContent, err := url2Stat(secondURL)
	if err != nil {
		ch <- diffMessage{
			Error: err.Trace(secondURL),
		}
		return
	}
	// if first target is a folder and second target is not then throw a type mismatch
	if firstContent.Type.IsDir() && !secondContent.Type.IsDir() {
		ch <- diffMessage{
			FirstURL:  firstContent.URL.String(),
			SecondURL: secondContent.URL.String(),
			Diff:      "type",
		}
		return
	}
	// if first target is a regular file, handle basic cases
	if firstContent.Type.IsRegular() {
		diffMsg := diffObjects(firstContent, secondContent)
		if diffMsg != nil {
			ch <- *diffMsg
		}
		return
	}
	// definitely first and second target are folders
	if recursive {
		diffFoldersRecursive(firstClnt, secondClnt, ch)
		return
	}
	diffFolders(firstClnt, secondClnt, ch)
}

// mainDiff main for 'diff'.
func mainDiff(ctx *cli.Context) {
	checkDiffSyntax(ctx)

	// Additional command speific theme customization.
	console.SetColor("DiffMessage", color.New(color.FgGreen, color.Bold))
	console.SetColor("DiffOnlyInFirst", color.New(color.FgRed, color.Bold))
	console.SetColor("DiffType", color.New(color.FgYellow, color.Bold))
	console.SetColor("DiffSize", color.New(color.FgMagenta, color.Bold))

	config := mustGetMcConfig()
	firstArg := ctx.Args().First()
	secondArg := ctx.Args().Last()

	firstURL := getAliasURL(firstArg, config.Aliases)
	secondURL := getAliasURL(secondArg, config.Aliases)

	newFirstURL := stripRecursiveURL(firstURL)
	for diff := range doDiffMain(newFirstURL, secondURL, isURLRecursive(firstURL)) {
		if diff.Error != nil {
			// Print in new line and adjust to top so that we don't print over the ongoing scan bar
			if !globalQuietFlag && !globalJSONFlag {
				console.Eraseline()
			}
		}
		fatalIf(diff.Error.Trace(newFirstURL, secondURL), "Failed to diff ‘"+firstURL+"’ and ‘"+secondURL+"’.")
		printMsg(diff)
	}
	// Print in new line and adjust to top so that we don't print over the ongoing scan bar
	if !globalQuietFlag && !globalJSONFlag {
		console.Eraseline()
	}
	console.Println(console.Colorize("DiffMessage", "Done."))
}