// Text Adventure -- main loop (finished).
//
// Run from this folder:
//   cd projects/04-text-adventure/finished
//   go run .

package main

import (
	"bufio"
	"fmt"
	"os"
	"slices"
	"strings"

	"textadventure/world"
)

var reader = bufio.NewReader(os.Stdin)
var currentRoom = world.StartID
var inventory = []string{}

func describe(room int) {
	fmt.Printf("-- %s --\n", world.Names[room])
	fmt.Println(world.Descriptions[room])

	if len(world.Items[room]) > 0 {
		fmt.Println("Items here: " + strings.Join(world.Items[room], ", "))
	}

	exitNames := []string{}
	for direction := range world.Exits[room] {
		exitNames = append(exitNames, direction)
	}
	slices.Sort(exitNames)
	fmt.Println("Exits: " + strings.Join(exitNames, ", "))
}

func goTo(direction string) {
	nextRoom, ok := world.Exits[currentRoom][direction]
	if !ok {
		fmt.Println("You cannot go that way.")
		return
	}
	currentRoom = nextRoom
	describe(currentRoom)
}

func take(itemName string) bool {
	items := world.Items[currentRoom]

	i := slices.Index(items, itemName)
	if i == -1 {
		fmt.Printf("There is no %s here.\n", itemName)
		return false
	}

	world.Items[currentRoom] = append(items[:i], items[i+1:]...)
	inventory = append(inventory, itemName)
	fmt.Printf("You pick up the %s.\n", itemName)

	if itemName == "gold coin" {
		fmt.Println("You found the treasure! You win!")
		return true
	}
	return false
}

func showInventory() {
	if len(inventory) == 0 {
		fmt.Println("You are carrying nothing.")
		return
	}
	fmt.Println("You are carrying: " + strings.Join(inventory, ", "))
}

// readLine prints the prompt and gives back one trimmed line. The error is
// not nil when there is no more input.
func readLine(prompt string) (string, error) {
	fmt.Print(prompt)
	text, err := reader.ReadString('\n')
	line := strings.TrimSpace(text)
	if err != nil && line == "" {
		return "", err
	}
	return line, nil
}

// parse splits a typed line into a verb and an argument. Items like
// "gold coin" are two words, so everything after the verb is the argument.
func parse(line string) (string, string) {
	words := strings.Fields(line)
	if len(words) == 0 {
		return "", ""
	}
	return words[0], strings.Join(words[1:], " ")
}

func main() {
	describe(currentRoom)

	for {
		line, err := readLine("> ")
		if err != nil {
			fmt.Println()
			fmt.Println("Goodbye.")
			break
		}

		verb, arg := parse(line)

		if verb == "" {
			continue // an empty line: ask again
		}

		if verb == "look" {
			describe(currentRoom)
		} else if verb == "go" {
			if arg == "" {
				fmt.Println("Go where?")
			} else {
				goTo(arg)
			}
		} else if verb == "take" {
			if arg == "" {
				fmt.Println("Take what?")
			} else if take(arg) {
				break
			}
		} else if verb == "inv" || verb == "inventory" {
			showInventory()
		} else if verb == "quit" {
			fmt.Println("Goodbye.")
			break
		} else {
			fmt.Printf("I do not understand '%s'.\n", verb)
		}
	}
}