package main

import (
	"bufio"
	"flag"
	"fmt"
	"log"
	"os"
	"regexp"
	"strings"
)

const deliminer = ","
const (
	Black   = "\033[30m"
	Red     = "\033[31m"
	Green   = "\033[32m"
	Yellow  = "\033[33m"
	Blue    = "\033[34m"
	Magenta = "\033[35m"
	Cyan    = "\033[36m"
	White   = "\033[37m"
)
const SourceColor = Magenta
const TargetColor = Yellow
const ErrorColor = Red
const DefaultColor = White
const PathColor = Green

var programName = os.Args[0]

type LinkInstruction struct {
	Source string
	Target string
	Force  bool
}

func main() {
	// Format:
	// source,target,force?
	log.SetFlags(log.Lmicroseconds)

	recurse := flag.String("r", "", "recurse into directories")
	file := flag.String("f", "", "file to read instructions from")
	flag.Parse()

	log.Printf("Recurse: %s", *recurse)
	log.Printf("File: %s", *file)

	var instructions []LinkInstruction
	if *recurse != "" {
		instructions, _ = ReadFromFilesRecursively(*recurse)
	} else if *file != "" {
		instructions, _ = ReadFromFile(*file)
	} else if len(os.Args) > 1 {
		instructions, _ = ReadFromArgs()
	} else {
		instructions, _ = ReadFromStdin()
	}

	if len(instructions) == 0 {
		log.Printf("No input provided")
		log.Printf("Provide input as: ")
		log.Printf("Arguments - %s <source>,<target>,<force?>", programName)
		log.Printf("File - %s -f <file>", programName)
		log.Printf("Folder (finding sync files in folder recursively) - %s -r <folder>", programName)
		log.Printf("stdin - (cat <file> | %s)", programName)
		os.Exit(1)
	}
	for _, instruction := range instructions {
		log.Printf("Processing: %s", InstructionToString(instruction))
		err := RunInstruction(instruction)
		if err != nil {
			log.Printf("Failed parsing instruction %s%s%s due to %s%+v%s", SourceColor, InstructionToString(instruction), DefaultColor, ErrorColor, err, DefaultColor)
			continue
		}
	}
}

func ReadFromFilesRecursively(input string) ([]LinkInstruction, error) {
	input = NormalizePath(input)
	log.Printf("Reading input from files recursively starting in %s%s%s", PathColor, input, DefaultColor)
	var instructions []LinkInstruction

	files, err := GetSyncFilesRecursively(input)
	if err != nil {
		log.Fatalf("Failed to get sync files recursively: %s%+v%s", ErrorColor, err, DefaultColor)
	}

	dirRegex, _ := regexp.Compile("^(.+?)sync$")
	for _, file := range files {
		file = NormalizePath(file)

		// This "has" to be done because instructions are resolved in relation to cwd
		fileDir := dirRegex.FindStringSubmatch(file)
		err := os.Chdir(fileDir[1])
		if err != nil {
			log.Fatalf("Failed to change directory to %s%s%s: %s%+v%s", SourceColor, fileDir[1], DefaultColor, ErrorColor, err, DefaultColor)
		}

		fileInstructions, _ := ReadFromFile(file)
		instructions = append(instructions, fileInstructions...)
	}
	return instructions, nil
}
func ReadFromFile(input string) ([]LinkInstruction, error) {
	input = NormalizePath(input)
	log.Printf("Reading input from file: %s%s%s", PathColor, input, DefaultColor)
	var instructions []LinkInstruction
	file, err := os.Open(input)
	if err != nil {
		log.Fatalf("Failed to open file %s%s%s: %s%+v%s", SourceColor, input, DefaultColor, ErrorColor, err, DefaultColor)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		instruction, err := ParseInstruction(line)
		if err != nil {
			log.Printf("Error parsing line: %s'%s'%s, error: %s%+v%s", SourceColor, line, DefaultColor, ErrorColor, err, DefaultColor)
			continue
		}
		instructions = append(instructions, instruction)
	}
	log.Printf("Read %d instructions from file", len(instructions))
	return instructions, nil
}
func ReadFromArgs() ([]LinkInstruction, error) {
	log.Printf("Reading input from args")
	var instructions []LinkInstruction
	for _, arg := range os.Args[1:] {
		instruction, err := ParseInstruction(arg)
		if err != nil {
			log.Printf("Error parsing arg: %s'%s'%s, error: %s%+v%s", SourceColor, arg, DefaultColor, ErrorColor, err, DefaultColor)
			continue
		}
		instructions = append(instructions, instruction)
	}
	log.Printf("Read %d instructions from args", len(instructions))
	return instructions, nil
}
func ReadFromStdin() ([]LinkInstruction, error) {
	log.Printf("Reading input from stdin")
	var instructions []LinkInstruction

	info, err := os.Stdin.Stat()
	if err != nil {
		log.Fatalf("Failed to stat stdin: %s%+v%s", ErrorColor, err, DefaultColor)
	}
	if info.Mode()&os.ModeNamedPipe != 0 {
		scanner := bufio.NewScanner(os.Stdin)
		for scanner.Scan() {
			line := scanner.Text()
			instruction, err := ParseInstruction(line)
			if err != nil {
				log.Printf("Error parsing line: %s'%s'%s, error: %s%+v%s", SourceColor, line, DefaultColor, ErrorColor, err, DefaultColor)
				continue
			}
			instructions = append(instructions, instruction)
		}
		if err := scanner.Err(); err != nil {
			log.Fatalf("Error reading from stdin: %s%+v%s", ErrorColor, err, DefaultColor)
		}
	}

	log.Printf("Read %d instructions from stdin", len(instructions))
	return instructions, nil
}

func ParseInstruction(line string) (LinkInstruction, error) {
	parts := strings.Split(line, deliminer)
	instruction := LinkInstruction{}

	if len(parts) < 2 {
		return instruction, fmt.Errorf("invalid format - not enough parameters (must have at least source and target)")
	}

	instruction.Source = parts[0]
	instruction.Target = parts[1]
	instruction.Force = false
	if len(parts) > 2 {
		res, _ := regexp.MatchString("^(?i)T|TRUE$", parts[2])
		instruction.Force = res
	}

	instruction.Source, _ = ConvertHome(instruction.Source)
	instruction.Target, _ = ConvertHome(instruction.Target)

	instruction.Source = NormalizePath(instruction.Source)
	instruction.Target = NormalizePath(instruction.Target)

	return instruction, nil
}

func RunInstruction(instruction LinkInstruction) error {
	if !FileExists(instruction.Source) {
		return fmt.Errorf("instruction source %s%s%s does not exist", SourceColor, instruction.Source, DefaultColor)
	}

	if AreSame(instruction.Source, instruction.Target) {
		log.Printf("Source %s%s%s and target %s%s%s are the same, nothing to do...", SourceColor, instruction.Source, DefaultColor, TargetColor, instruction.Target, DefaultColor)
		return nil
	}

	if FileExists(instruction.Target) {
		if instruction.Force {
			isSymlink, err := IsSymlink(instruction.Target)
			if err != nil {
				return fmt.Errorf("could not determine whether %s%s%s is a sym link or not, stopping; err: %s%+v%s", TargetColor, instruction.Target, DefaultColor, ErrorColor, err, DefaultColor)
			}

			if isSymlink {
				log.Printf("Removing symlink at %s%s%s", TargetColor, instruction.Target, DefaultColor)
				err = os.Remove(instruction.Target)
				if err != nil {
					return fmt.Errorf("failed deleting %s%s%s due to %s%+v%s", TargetColor, instruction.Target, DefaultColor, ErrorColor, err, DefaultColor)
				}
			} else {
				return fmt.Errorf("refusing to delte actual (non symlink) file %s%s%s", TargetColor, instruction.Target, DefaultColor)
			}
		} else {
			return fmt.Errorf("target %s%s%s exists - handle manually or set the 'forced' flag (3rd field)", TargetColor, instruction.Target, DefaultColor)
		}
	}

	err := os.Symlink(instruction.Source, instruction.Target)
	if err != nil {
		return fmt.Errorf("failed creating symlink between %s%s%s and %s%s%s with error %s%+v%s", SourceColor, instruction.Source, DefaultColor, TargetColor, instruction.Target, DefaultColor, ErrorColor, err, DefaultColor)
	}

	return nil
}
