package me.viper.teamplugin.gui;

import me.viper.teamplugin.manager.LangManager;
import me.viper.teamplugin.manager.MailboxManager;
import me.viper.teamplugin.manager.MessageManager;
import me.viper.teamplugin.util.Utils;
import org.bukkit.Bukkit;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;

import java.util.*;

/**
 * MailboxGUI – two-view postfach for TeamPlugin.
 *
 *  LIST VIEW  (54 slots)
 *  ┌─────────────────────────┐
 *  │  Header row (glass)     │  slot 4 = mailbox info item
 *  │  Message items 9-44     │  WRITTEN_BOOK=unread, BOOK=read
 *  │  Footer nav  45/49/53   │  ← page | close | page →
 *  └─────────────────────────┘
 *
 *  READ VIEW  (54 slots)
 *  ┌─────────────────────────┐
 *  │  Background filler      │
 *  │  Full message at 22     │
 *  │  Delete:20  Reply:24    │
 *  │  Back:49                │
 *  └─────────────────────────┘
 */
public class MailboxGUI {

    private static final int ITEMS_PER_PAGE = 36; // rows 1-4, slots 9-44

    /** UUID → current list-view page number */
    private static final Map<UUID, Integer> CURRENT_PAGE    = new HashMap<>();
    /** UUID → whose mailbox is open (player name) */
    private static final Map<UUID, String>  OPEN_FOR_PLAYER = new HashMap<>();
    /** UUID → msgId of message currently being read */
    private static final Map<UUID, String>  READING_ID      = new HashMap<>();

    // ── Open: list view ───────────────────────────────────────────────

    /** Opens the caller's own mailbox at page 0. */
    public static void openMailbox(Player viewer) {
        openMailbox(viewer, viewer.getName(), 0);
    }

    /** Opens a specific player's mailbox at a given page (admins can inspect others). */
    public static void openMailbox(Player viewer, String targetPlayer, int page) {
        List<String[]> messages = MailboxManager.getParsedMessages(targetPlayer);
        int totalPages = Math.max(1, (int) Math.ceil((double) messages.size() / ITEMS_PER_PAGE));
        page = Math.max(0, Math.min(page, totalPages - 1));

        OPEN_FOR_PLAYER.put(viewer.getUniqueId(), targetPlayer);
        CURRENT_PAGE.put(viewer.getUniqueId(), page);

        Inventory inv = Bukkit.createInventory(null, 54, Utils.color(getListTitle()));

        // Header row
        ItemStack headerGlass = filler(Material.CYAN_STAINED_GLASS_PANE);
        for (int i = 0; i < 9; i++) inv.setItem(i, headerGlass);

        // Footer row
        ItemStack footerGlass = filler(Material.BLACK_STAINED_GLASS_PANE);
        for (int i = 45; i < 54; i++) inv.setItem(i, footerGlass);

        // Info item (slot 4)
        int unread = MailboxManager.getUnreadCount(targetPlayer);
        inv.setItem(4, buildInfoItem(targetPlayer, unread, page + 1, totalPages));

        // Message items (slots 9-44)
        int start = page * ITEMS_PER_PAGE;
        for (int i = 0; i < ITEMS_PER_PAGE; i++) {
            int idx = start + i;
            if (idx >= messages.size()) break;
            inv.setItem(9 + i, buildMessageListItem(messages.get(idx)));
        }

        // Navigation
        if (page > 0) inv.setItem(45, navItem(Material.ARROW,
                Utils.color(LangManager.get("mailbox_prev_page")),
                List.of(Utils.color("&7Vorherige Seite"))));

        inv.setItem(49, navItem(Material.BARRIER,
                Utils.color(LangManager.get("mailbox_close")),
                List.of(Utils.color("&7Postfach schließen"))));

        if (page + 1 < totalPages) inv.setItem(53, navItem(Material.ARROW,
                Utils.color(LangManager.get("mailbox_next_page")),
                List.of(Utils.color("&7Nächste Seite"))));

        viewer.openInventory(inv);
    }

    // ── Open: read view ───────────────────────────────────────────────

    private static void openMessage(Player viewer, String[] parts) {
        // parts: [id, from, isoTimestamp, read, text]
        String msgId = parts[0];
        String from  = parts[1];
        String date  = Utils.prettifyIso(parts[2]);
        String text  = parts[4];

        READING_ID.put(viewer.getUniqueId(), msgId);

        String targetPlayer = OPEN_FOR_PLAYER.getOrDefault(viewer.getUniqueId(), viewer.getName());
        MailboxManager.markRead(targetPlayer, msgId);

        Inventory inv = Bukkit.createInventory(null, 54, Utils.color(getReadTitle()));

        // Background
        ItemStack bg = filler(Material.GRAY_STAINED_GLASS_PANE);
        for (int i = 0; i < 54; i++) inv.setItem(i, bg);

        // Message paper at slot 22
        inv.setItem(22, buildFullMessageItem(from, date, text));

        // Delete (slot 20)
        inv.setItem(20, navItem(Material.RED_CONCRETE,
                Utils.color(LangManager.get("mailbox_delete_btn")),
                List.of(Utils.color("&7Nachricht endgültig löschen"))));

        // Reply (slot 24)
        inv.setItem(24, navItem(Material.WRITABLE_BOOK,
                Utils.color(Utils.replace(LangManager.get("mailbox_reply_btn"), "%player%", from)),
                List.of(Utils.color("&7An &b" + from + " &7antworten"))));

        // Back (slot 49)
        inv.setItem(49, navItem(Material.ARROW,
                Utils.color(LangManager.get("mailbox_back_btn")),
                List.of(Utils.color("&7Zurück zur Liste"))));

        viewer.openInventory(inv);
    }

    // ── Click handlers ────────────────────────────────────────────────

    public static void handleListClick(Player player, InventoryClickEvent e) {
        e.setCancelled(true);
        int slot = e.getRawSlot();
        ItemStack clicked = e.getCurrentItem();
        if (clicked == null || clicked.getType().isAir()) return;

        String target = OPEN_FOR_PLAYER.getOrDefault(player.getUniqueId(), player.getName());
        int page = CURRENT_PAGE.getOrDefault(player.getUniqueId(), 0);

        switch (slot) {
            case 45 -> openMailbox(player, target, page - 1);
            case 49 -> {
                cleanup(player.getUniqueId());
                player.closeInventory();
            }
            case 53 -> openMailbox(player, target, page + 1);
            default -> {
                if (slot >= 9 && slot <= 44) {
                    List<String[]> messages = MailboxManager.getParsedMessages(target);
                    int idx = page * ITEMS_PER_PAGE + (slot - 9);
                    if (idx < messages.size()) openMessage(player, messages.get(idx));
                }
            }
        }
    }

    public static void handleReadClick(Player player, InventoryClickEvent e) {
        e.setCancelled(true);
        int slot = e.getRawSlot();
        ItemStack clicked = e.getCurrentItem();
        if (clicked == null || clicked.getType().isAir()) return;

        String target = OPEN_FOR_PLAYER.getOrDefault(player.getUniqueId(), player.getName());
        String msgId  = READING_ID.get(player.getUniqueId());
        int    page   = CURRENT_PAGE.getOrDefault(player.getUniqueId(), 0);

        switch (slot) {
            case 20 -> { // delete
                if (msgId != null) MailboxManager.delete(target, msgId);
                READING_ID.remove(player.getUniqueId());
                player.sendMessage(Utils.color(LangManager.get("mail_deleted")));
                openMailbox(player, target, page);
            }
            case 24 -> { // reply
                if (msgId != null) {
                    MailboxManager.getParsedMessages(target).stream()
                            .filter(a -> a[0].equals(msgId))
                            .findFirst()
                            .ifPresent(parts -> {
                                cleanup(player.getUniqueId());
                                player.closeInventory();
                                MessageManager.startReply(player, parts[1]);
                            });
                }
            }
            case 49 -> { // back
                READING_ID.remove(player.getUniqueId());
                openMailbox(player, target, page);
            }
        }
    }

    // ── Title helpers ─────────────────────────────────────────────────

    public static String getListTitle() {
        return LangManager.get("mailbox_title");
    }

    public static String getReadTitle() {
        return LangManager.get("mailbox_read_title");
    }

    public static boolean isListTitle(String colored) {
        return colored.equals(Utils.color(getListTitle()));
    }

    public static boolean isReadTitle(String colored) {
        return colored.equals(Utils.color(getReadTitle()));
    }

    // ── State cleanup ─────────────────────────────────────────────────

    public static void cleanup(UUID uuid) {
        CURRENT_PAGE.remove(uuid);
        OPEN_FOR_PLAYER.remove(uuid);
        READING_ID.remove(uuid);
    }

    // ── Item builders ─────────────────────────────────────────────────

    private static ItemStack buildInfoItem(String owner, int unread, int page, int total) {
        ItemStack item = new ItemStack(Material.ENCHANTED_BOOK);
        ItemMeta m = item.getItemMeta();
        if (m != null) {
            m.setDisplayName(Utils.color("&b&lPostfach &8– &7" + owner));
            m.setLore(List.of(
                    Utils.color("&7Ungelesen&8: &e" + unread),
                    Utils.color("&7Seite &e" + page + " &7/ &e" + total)
            ));
            item.setItemMeta(m);
        }
        return item;
    }

    private static ItemStack buildMessageListItem(String[] parts) {
        // parts: [id, from, iso, read, text]
        boolean read = "true".equals(parts[3]);
        ItemStack item = new ItemStack(read ? Material.BOOK : Material.WRITTEN_BOOK);
        ItemMeta m = item.getItemMeta();
        if (m != null) {
            m.setDisplayName(Utils.color((read ? "&7" : "&e&l") + "Von: " + parts[1]));
            String preview = parts[4].length() > 38 ? parts[4].substring(0, 38) + "…" : parts[4];
            m.setLore(List.of(
                    Utils.color("&7" + Utils.prettifyIso(parts[2])),
                    Utils.color("&f" + preview),
                    "",
                    Utils.color(read ? "&8Gelesen" : "&eUngelesen – Klicken zum Lesen")
            ));
            item.setItemMeta(m);
        }
        return item;
    }

    private static ItemStack buildFullMessageItem(String from, String date, String text) {
        ItemStack item = new ItemStack(Material.PAPER);
        ItemMeta m = item.getItemMeta();
        if (m != null) {
            m.setDisplayName(Utils.color("&bVon: &e" + from + " &8| &7" + date));
            List<String> lore = new ArrayList<>();
            lore.add("");
            for (String line : wrapText(text, 40)) lore.add(Utils.color("&f" + line));
            m.setLore(lore);
            item.setItemMeta(m);
        }
        return item;
    }

    // ── Generic helpers ───────────────────────────────────────────────

    private static ItemStack filler(Material mat) {
        ItemStack item = new ItemStack(mat);
        ItemMeta m = item.getItemMeta();
        if (m != null) { m.setDisplayName(" "); item.setItemMeta(m); }
        return item;
    }

    private static ItemStack navItem(Material mat, String name, List<String> lore) {
        ItemStack item = new ItemStack(mat);
        ItemMeta m = item.getItemMeta();
        if (m != null) { m.setDisplayName(name); m.setLore(lore); item.setItemMeta(m); }
        return item;
    }

    /** Word-wraps {@code text} at {@code maxChars} characters per line. */
    private static List<String> wrapText(String text, int maxChars) {
        List<String> lines = new ArrayList<>();
        String[] words = text.split(" ");
        StringBuilder cur = new StringBuilder();
        for (String w : words) {
            if (cur.length() > 0 && cur.length() + 1 + w.length() > maxChars) {
                lines.add(cur.toString());
                cur = new StringBuilder(w);
            } else {
                if (cur.length() > 0) cur.append(' ');
                cur.append(w);
            }
        }
        if (cur.length() > 0) lines.add(cur.toString());
        return lines.isEmpty() ? List.of(text) : lines;
    }
}