package cli

import (
	"fmt"
	"os"
	"os/exec"
	"reflect"
	"strconv"
	"strings"
	"time"
)

// InputFromEditor retrieves user input by opening an editor (one specified by
// $EDITOR or 'vim' if $EDITOR is not set) on a temporary file. Once the editor
// closes, the contents of the file are read and the file is deleted. If the
// contents of the file exactly match the value of placeholder (no edits to the
// file were made), then an empty string is returned. Otherwise, the contents
// are returned. Example patten: message.*.md
func InputFromEditor(placeholder string, pattern string) (string, error) {
	msgFile, _ := os.CreateTemp("/tmp", pattern)
	defer os.Remove(msgFile.Name())

	os.WriteFile(msgFile.Name(), []byte(placeholder), os.ModeAppend)

	editor := os.Getenv("EDITOR")
	if editor == "" {
		editor = "vim" // default to vim if no EDITOR env variable
	}

	execCmd := exec.Command(editor, msgFile.Name())
	execCmd.Stdin = os.Stdin
	execCmd.Stdout = os.Stdout
	execCmd.Stderr = os.Stderr

	if err := execCmd.Run(); err != nil {
		return "", err
	}

	bytes, _ := os.ReadFile(msgFile.Name())
	content := string(bytes)

	if placeholder != "" {
		if content == placeholder {
			return "", nil
		}

		// strip placeholder if content begins with it
		if strings.HasPrefix(content, placeholder) {
			content = content[len(placeholder):]
		}
	}

	return strings.Trim(content, "\n \t"), nil
}

// humanTimeElapsedSince returns a human-friendly "in the past" representation
// of the given duration.
func humanTimeElapsedSince(d time.Duration) string {
	seconds := d.Seconds()
	minutes := seconds / 60
	hours := minutes / 60
	days := hours / 24
	weeks := days / 7
	months := days / 30
	years := days / 365

	switch {
	case seconds < 60:
		return "seconds ago"
	case minutes < 2:
		return "1 minute ago"
	case minutes < 60:
		return fmt.Sprintf("%d minutes ago", int64(minutes))
	case hours < 2:
		return "1 hour ago"
	case hours < 24:
		return fmt.Sprintf("%d hours ago", int64(hours))
	case days < 2:
		return "1 day ago"
	case days < 7:
		return fmt.Sprintf("%d days ago", int64(days))
	case weeks < 2:
		return "1 week ago"
	case weeks <= 4:
		return fmt.Sprintf("%d weeks ago", int64(weeks))
	case months < 2:
		return "1 month ago"
	case months < 12:
		return fmt.Sprintf("%d months ago", int64(months))
	case years < 2:
		return "1 year ago"
	default:
		return fmt.Sprintf("%d years ago", int64(years))
	}
}

// SetStructDefaultValues checks for any nil ptr fields within the passed
// struct, and sets the values of those fields to the value that is defined by
// their "default" struct tag. Handles setting string, int, and bool values.
// Returns whether any changes were made to the struct.
func SetStructDefaults(data interface{}) bool {
	v := reflect.ValueOf(data).Elem()
	changed := false

	for i := 0; i < v.NumField(); i++ {
		field := v.Field(i)

		// Check if we can set the field's value
		if !field.CanSet() {
			continue
		}

		// We won't bother with non-pointer fields
		if field.Kind() != reflect.Ptr {
			continue
		}

		t := field.Type() // type of pointer
		e := t.Elem()     // type of value of pointer

		// Handle nested structs recursively
		if e.Kind() == reflect.Struct {
			if field.IsNil() {
				field.Set(reflect.New(e))
				changed = true
			}
			result := SetStructDefaults(field.Interface())
			if result {
				changed = true
			}
			continue
		}

		if !field.IsNil() {
			continue
		}

		// Get the "default" struct tag
		defaultTag := v.Type().Field(i).Tag.Get("default")
		if defaultTag == "" {
			continue
		}

		// Set nil pointer fields to their defined defaults
		switch e.Kind() {
		case reflect.String:
			defaultValue := defaultTag
			field.Set(reflect.ValueOf(&defaultValue))
		case reflect.Int, reflect.Int32, reflect.Int64:
			intValue, _ := strconv.ParseInt(defaultTag, 10, 64)
			field.Set(reflect.New(e))
			field.Elem().SetInt(intValue)
		case reflect.Bool:
			boolValue := defaultTag == "true"
			field.Set(reflect.ValueOf(&boolValue))
		}
		changed = true
	}
	return changed
}