package commands

import (
	"regexp"
	"testing"
	"unicode/utf8"

	"github.com/bwmarrin/discordgo"
)

// Discord refuses a command that is over its limits, and then the whole
// command silently doesn't exist. These checks catch that in a test instead
// of after a deploy. See
// https://discord.com/developers/docs/interactions/application-commands

var commandName = regexp.MustCompile(`^[-_\p{L}\p{N}]{1,32}$`)

func checkOptions(t *testing.T, path string, options []*discordgo.ApplicationCommandOption, size *int) {
	t.Helper()
	if len(options) > 25 {
		t.Errorf("%s: %d options, at most 25 allowed", path, len(options))
	}
	seen := map[string]bool{}
	sawOptional := false
	for _, o := range options {
		where := path + " " + o.Name
		if !commandName.MatchString(o.Name) || o.Name != lower(o.Name) {
			t.Errorf("%s: option names are 1 to 32 lowercase letters, digits, - or _", where)
		}
		if seen[o.Name] {
			t.Errorf("%s: duplicate option name", where)
		}
		seen[o.Name] = true
		if n := utf8.RuneCountInString(o.Description); n < 1 || n > 100 {
			t.Errorf("%s: description is %d characters, must be 1 to 100", where, n)
		}
		*size += utf8.RuneCountInString(o.Name) + utf8.RuneCountInString(o.Description)
		if len(o.Choices) > 25 {
			t.Errorf("%s: %d choices, at most 25", where, len(o.Choices))
		}
		for _, c := range o.Choices {
			*size += utf8.RuneCountInString(c.Name)
			if s, ok := c.Value.(string); ok {
				*size += utf8.RuneCountInString(s)
				if utf8.RuneCountInString(s) > 100 || utf8.RuneCountInString(c.Name) > 100 {
					t.Errorf("%s: a choice is over 100 characters", where)
				}
			}
		}
		switch o.Type {
		case discordgo.ApplicationCommandOptionSubCommand, discordgo.ApplicationCommandOptionSubCommandGroup:
			if len(o.Options) == 0 && o.Type == discordgo.ApplicationCommandOptionSubCommandGroup {
				t.Errorf("%s: a group needs subcommands", where)
			}
			checkOptions(t, where, o.Options, size)
		default:
			// Required options come before optional ones.
			if o.Required && sawOptional {
				t.Errorf("%s: a required option after an optional one", where)
			}
			if !o.Required {
				sawOptional = true
			}
		}
	}
}

func lower(s string) string {
	out := []rune(s)
	for i, r := range out {
		if r >= 'A' && r <= 'Z' {
			out[i] = r + 32
		}
	}
	return string(out)
}

func TestCommandsStayWithinDiscordLimits(t *testing.T) {
	all := append(append(append([]*discordgo.ApplicationCommand{}, AllCommands...), BetaCommands...), OwnerCommands...)
	names := map[string]bool{}
	for _, c := range all {
		if names[c.Name] {
			t.Errorf("/%s is defined twice", c.Name)
		}
		names[c.Name] = true
		if !commandName.MatchString(c.Name) || c.Name != lower(c.Name) {
			t.Errorf("/%s: names are 1 to 32 lowercase letters, digits, - or _", c.Name)
		}
		if n := utf8.RuneCountInString(c.Description); n < 1 || n > 100 {
			t.Errorf("/%s: description is %d characters, must be 1 to 100", c.Name, n)
		}
		size := utf8.RuneCountInString(c.Name) + utf8.RuneCountInString(c.Description)
		checkOptions(t, "/"+c.Name, c.Options, &size)
		if size > 8000 {
			t.Errorf("/%s: %d characters in total, Discord allows 8000", c.Name, size)
		}
		if _, ok := handlers[c.Name]; !ok {
			t.Errorf("/%s has no handler", c.Name)
		}
	}
	for name := range handlers {
		if !names[name] {
			t.Errorf("a handler for /%s exists but the command is never registered", name)
		}
	}
}