package adventure

import "strings"

type parsedCommand struct {
	verb   string
	object string
}

// directionAliases maps shorthand and full direction names to canonical forms.
var directionAliases = map[string]string{
	"n":     "north",
	"s":     "south",
	"e":     "east",
	"w":     "west",
	"u":     "up",
	"d":     "down",
	"north": "north",
	"south": "south",
	"east":  "east",
	"west":  "west",
	"up":    "up",
	"down":  "down",
}

// verbAliases maps aliases to canonical verbs.
var verbAliases = map[string]string{
	"look":    "look",
	"l":       "look",
	"examine": "look",
	"inspect": "look",
	"x":       "look",
	"go":      "go",
	"move":    "go",
	"walk":    "go",
	"take":    "take",
	"get":     "take",
	"grab":    "take",
	"pick":    "take",
	"drop":    "drop",
	"put":     "drop",
	"use":     "use",
	"apply":   "use",
	"inventory": "inventory",
	"inv":       "inventory",
	"i":         "inventory",
	"help":      "help",
	"?":         "help",
	"quit":      "quit",
	"exit":      "quit",
	"logout":    "quit",
	"q":         "quit",
}

// articles are stripped from input.
var articles = map[string]bool{
	"the": true,
	"a":   true,
	"an":  true,
}

// parseCommand parses raw input into a verb and object.
func parseCommand(input string) parsedCommand {
	input = strings.TrimSpace(strings.ToLower(input))
	if input == "" {
		return parsedCommand{}
	}

	words := strings.Fields(input)

	// Strip articles.
	var filtered []string
	for _, w := range words {
		if !articles[w] {
			filtered = append(filtered, w)
		}
	}
	if len(filtered) == 0 {
		return parsedCommand{}
	}

	first := filtered[0]

	// Bare direction → go <direction>.
	if dir, ok := directionAliases[first]; ok {
		return parsedCommand{verb: "go", object: dir}
	}

	// Known verb alias.
	if verb, ok := verbAliases[first]; ok {
		object := ""
		if len(filtered) > 1 {
			object = strings.Join(filtered[1:], " ")
			// Resolve direction alias in object for "go north" etc.
			if verb == "go" {
				if dir, ok := directionAliases[object]; ok {
					object = dir
				}
			}
		}
		return parsedCommand{verb: verb, object: object}
	}

	// Unknown verb — return as-is so game can give an error.
	return parsedCommand{verb: first, object: strings.Join(filtered[1:], " ")}
}