package main

import (
	"fmt"
	"log"
	"os"
	"path"
	"regexp"
	"strconv"
	"strings"
)

type LinkInstruction struct {
	Source string
	Target string
	Force  bool
	Hard   bool
}

func (instruction *LinkInstruction) String() string {
	return fmt.Sprintf("%s%s%s%s%s%s%s%s%s%s%s", SourceColor, instruction.Source, DefaultColor, deliminer, TargetColor, instruction.Target, DefaultColor, deliminer, strconv.FormatBool(instruction.Force), deliminer, strconv.FormatBool(instruction.Hard))
}

func ParseInstruction(line string) (LinkInstruction, error) {
	line = strings.TrimSpace(line)
	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 = strings.TrimSpace(parts[0])
	instruction.Target = strings.TrimSpace(parts[1])
	instruction.Force = false
	if len(parts) > 2 {
		res, _ := regexp.MatchString(`^(?i)\s*T|TRUE\s*$`, parts[2])
		instruction.Force = res
	}
	if len(parts) > 3 {
		res, _ := regexp.MatchString(`^(?i)\s*T|TRUE\s*$`, parts[3])
		instruction.Hard = 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 (instruction *LinkInstruction) RunSync() 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, %snothing to do...%s", SourceColor, instruction.Source, DefaultColor, TargetColor, instruction.Target, DefaultColor, PathColor, 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)
	}
	log.Printf("Created symlink between %s%s%s and %s%s%s", SourceColor, instruction.Source, DefaultColor, TargetColor, instruction.Target, DefaultColor)

	return nil
}

func (instruction *LinkInstruction) RunAsync(status chan (error)) {
	defer close(status)
	if !FileExists(instruction.Source) {
		status <- fmt.Errorf("instruction source %s%s%s does not exist", SourceColor, instruction.Source, DefaultColor)
		return
	}

	if AreSame(instruction.Source, instruction.Target) {
		status <- fmt.Errorf("source %s%s%s and target %s%s%s are the same, %snothing to do...%s", SourceColor, instruction.Source, DefaultColor, TargetColor, instruction.Target, DefaultColor, PathColor, DefaultColor)
		return
	}

	if FileExists(instruction.Target) {
		if instruction.Force {
			isSymlink, err := IsSymlink(instruction.Target)
			if err != nil {
				status <- 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)
				return
			}

			if instruction.Hard {
				info, err := os.Stat(instruction.Target)
				if err != nil {
					status <- fmt.Errorf("could not stat %s%s%s, stopping; err: %s%+v%s", TargetColor, instruction.Target, DefaultColor, ErrorColor, err, DefaultColor)
					return
				}
				if info.Mode().IsRegular() && info.Name() == path.Base(instruction.Source) {
					log.Printf("Overwriting existing file %s%s%s", TargetColor, instruction.Target, DefaultColor)
					err := os.Remove(instruction.Target)
					if err != nil {
						status <- fmt.Errorf("could not remove existing file %s%s%s; err: %s%+v%s", TargetColor, instruction.Target, DefaultColor, ErrorColor, err, DefaultColor)
						return
					}
				}
			}

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

	var err error
	if instruction.Hard {
		err = os.Link(instruction.Source, instruction.Target)
	} else {
		err = os.Symlink(instruction.Source, instruction.Target)
	}
	if err != nil {
		status <- 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
	}
	log.Printf("Created symlink between %s%s%s and %s%s%s", SourceColor, instruction.Source, DefaultColor, TargetColor, instruction.Target, DefaultColor)

	status <- nil
}