package main

import (
	"bufio"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

// runGuided is what happens when somebody double-clicks the program instead of
// typing its name at a prompt.
//
// Without this, Explorer opens a console, main() finds no arguments, prints
// the usage text to stderr and exits — and Windows destroys the window in the
// same instant. From the other side of the screen that is indistinguishable
// from a crash. So when we know we were double-clicked, we ask the one
// question the program actually needs and stay on screen until the reader is
// done.
//
// This path is entered ONLY when there are no arguments and both ends of the
// program are a real console. Any scripted or piped use takes exactly the same
// code path it always did.
//
// Guided mode runs the scan and nothing else. PhotoSweep's clean command can
// move files into a quarantine folder, so it is deliberately never offered
// here: a person who double-clicked an unfamiliar program should not be one
// keypress away from their photo library being rearranged.
func runGuided() {
	in := bufio.NewScanner(os.Stdin)

	fmt.Println()
	fmt.Println("  PhotoSweep")
	fmt.Println("  Find photos that are the same picture twice.")
	fmt.Println()
	fmt.Println("  Point it at a folder and it compares how every picture actually")
	fmt.Println("  looks, so it spots the same shot saved twice at different sizes or")
	fmt.Println("  qualities, burst frames, and re-edited copies — not just files that")
	fmt.Println("  happen to be identical.")
	fmt.Println()
	fmt.Println("  This only lists what it finds. Nothing is moved or deleted.")
	fmt.Println()

	suggested := suggestedFolder()
	for {
		fmt.Println("  Which folder of photos shall I look through?")
		if suggested != "" {
			fmt.Printf("  (press Enter for %s)\n", suggested)
		}
		fmt.Print("  > ")

		if !in.Scan() {
			// stdin closed on us; there is nothing sensible left to ask.
			return
		}
		answer := strings.TrimSpace(in.Text())
		answer = strings.Trim(answer, `"`)
		if answer == "" {
			answer = suggested
		}
		if answer == "" {
			fmt.Println()
			fmt.Println("  I need a folder to look through. Try again, or close this window.")
			fmt.Println()
			continue
		}

		info, err := os.Stat(answer)
		switch {
		case err != nil:
			fmt.Println()
			fmt.Printf("  I cannot find %q.\n", answer)
			fmt.Println("  Tip: you can drag a folder from Explorer onto this window to")
			fmt.Println("  paste its location, then press Enter.")
			fmt.Println()
			continue
		case !info.IsDir():
			fmt.Println()
			fmt.Printf("  %q is a file, not a folder. Give me the folder it sits in.\n", answer)
			fmt.Println()
			continue
		}

		fmt.Println()
		fmt.Println("  Working. Every photo has to be opened and fingerprinted, so a big")
		fmt.Println("  library can take a few minutes.")
		fmt.Println()
		cmdScan([]string{answer})
		break
	}

	fmt.Println()
	fmt.Println("  Done. Nothing was changed — that list is only a report.")
	fmt.Println("  Run it again any time on another folder.")
	fmt.Println("  There is a command-line version too: photosweep help")
	pause(in)
}

// suggestedFolder offers somewhere worth looking that is certain to exist, so
// the reader can get a useful answer by pressing one key.
func suggestedFolder() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return ""
	}
	// Near-duplicates collect where photographs land: the picture library
	// first, then the download folder they often arrive in.
	for _, name := range []string{"Pictures", "Downloads"} {
		candidate := filepath.Join(home, name)
		if info, err := os.Stat(candidate); err == nil && info.IsDir() {
			return candidate
		}
	}
	return home
}

// pause keeps the console window open. Explorer closes it the moment the
// process exits, so without this the reader never sees the output.
func pause(in *bufio.Scanner) {
	fmt.Println()
	fmt.Print("  Press Enter to close this window. ")
	in.Scan()
}