"use client";

import { useState, useMemo } from "react";
import type { Log, LogType } from "@/types";
import { dateIST, fmtTime } from "@/lib/date-ist";

const TYPE_COLORS: Record<LogType, string> = {
  feed:   "bg-rose-400",
  sleep:  "bg-blue-400",
  diaper: "bg-amber-400",
};

function getIcon(type: LogType) {
  if (type === "feed")   return "🍼";
  if (type === "sleep")  return "😴";
  if (type === "diaper") return "🚼";
  return "📝";
}

interface Props {
  logs: Log[];
  filter: LogType | "all";
}

export function CalendarView({ logs, filter }: Props) {
  const now = new Date();
  const [calMonth, setCalMonth]   = useState(new Date(now.getFullYear(), now.getMonth(), 1));
  const [selectedDay, setSelectedDay] = useState<string | null>(now.toISOString().slice(0, 10));

  const year  = calMonth.getFullYear();
  const month = calMonth.getMonth();
  const today = now.toISOString().slice(0, 10);
  const isCurrentMonth = year === now.getFullYear() && month === now.getMonth();

  const filteredLogs = filter === "all" ? logs : logs.filter(l => l.type === filter);

  const logsByDate = useMemo(() => {
    const map: Record<string, Log[]> = {};
    filteredLogs.forEach(log => {
      const key = dateIST(log.loggedAt); // IST date, not UTC
      if (!map[key]) map[key] = [];
      map[key].push(log);
    });
    return map;
  }, [filteredLogs]);

  const firstDow    = new Date(year, month, 1).getDay();
  const daysInMonth = new Date(year, month + 1, 0).getDate();
  const cells: (number | null)[] = [
    ...Array(firstDow).fill(null),
    ...Array.from({ length: daysInMonth }, (_, i) => i + 1),
  ];

  const dayKey = (d: number) =>
    `${year}-${String(month + 1).padStart(2, "0")}-${String(d).padStart(2, "0")}`;

  const selectedLogs = useMemo(
    () =>
      selectedDay
        ? (logsByDate[selectedDay] || [])
            .slice()
            .sort((a, b) => new Date(b.loggedAt).getTime() - new Date(a.loggedAt).getTime())
        : [],
    [selectedDay, logsByDate],
  );

  return (
    <div className="space-y-3">
      <div className="bg-white dark:bg-gray-800 rounded-xl p-4">
        {/* Month nav */}
        <div className="flex items-center justify-between mb-4">
          <button
            onClick={() => setCalMonth(new Date(year, month - 1, 1))}
            className="w-8 h-8 flex items-center justify-center rounded-lg hover:bg-gray-100 dark:hover:bg-gray-700 text-gray-600 dark:text-gray-300 text-lg"
          >
            ‹
          </button>
          <span className="font-semibold text-gray-800 dark:text-white">
            {calMonth.toLocaleDateString("en-US", { month: "long", year: "numeric" })}
          </span>
          <button
            onClick={() => setCalMonth(new Date(year, month + 1, 1))}
            disabled={isCurrentMonth}
            className="w-8 h-8 flex items-center justify-center rounded-lg hover:bg-gray-100 dark:hover:bg-gray-700 text-gray-600 dark:text-gray-300 text-lg disabled:opacity-30"
          >
            ›
          </button>
        </div>

        {/* DOW headers */}
        <div className="grid grid-cols-7 mb-1">
          {["Su", "Mo", "Tu", "We", "Th", "Fr", "Sa"].map(d => (
            <div key={d} className="text-center text-xs text-gray-400 font-medium py-1">{d}</div>
          ))}
        </div>

        {/* Day cells */}
        <div className="grid grid-cols-7 gap-y-1">
          {cells.map((day, i) => {
            if (!day) return <div key={i} />;
            const key     = dayKey(day);
            const dayLogs = logsByDate[key] || [];
            const isToday = key === today;
            const isSel   = key === selectedDay;
            const types   = [...new Set(dayLogs.map(l => l.type))] as LogType[];

            return (
              <button
                key={i}
                onClick={() => setSelectedDay(isSel ? null : key)}
                className={`flex flex-col items-center justify-center py-1.5 rounded-lg transition-colors ${
                  isSel   ? "bg-rose-400" :
                  isToday ? "bg-rose-50 dark:bg-rose-900/30" :
                            "hover:bg-gray-50 dark:hover:bg-gray-700"
                }`}
              >
                <span className={`text-sm leading-none ${
                  isSel   ? "text-white font-semibold" :
                  isToday ? "text-rose-500 font-bold"  :
                            "text-gray-700 dark:text-gray-300"
                }`}>
                  {day}
                </span>
                <div className="flex gap-0.5 mt-1 h-2 items-center">
                  {types.slice(0, 3).map(t => (
                    <span key={t} className={`w-1.5 h-1.5 rounded-full ${isSel ? "bg-white/80" : TYPE_COLORS[t]}`} />
                  ))}
                </div>
              </button>
            );
          })}
        </div>

        {/* Legend */}
        <div className="flex justify-center gap-5 mt-4 pt-3 border-t border-gray-100 dark:border-gray-700">
          {(["feed", "sleep", "diaper"] as LogType[]).map(t => (
            <div key={t} className="flex items-center gap-1.5 text-xs text-gray-500 dark:text-gray-400">
              <span className={`w-2 h-2 rounded-full ${TYPE_COLORS[t]}`} />
              <span className="capitalize">{t}</span>
            </div>
          ))}
        </div>
      </div>

      {/* Selected day detail */}
      {selectedDay && (
        <div className="bg-white dark:bg-gray-800 rounded-xl p-4">
          <div className="flex items-center justify-between mb-3">
            <h3 className="font-semibold text-gray-800 dark:text-white">
              {new Date(selectedDay + "T12:00:00").toLocaleDateString("en-US", {
                weekday: "long", month: "short", day: "numeric",
              })}
            </h3>
            <span className="text-sm text-gray-400 dark:text-gray-500">
              {selectedLogs.length} {selectedLogs.length === 1 ? "entry" : "entries"}
            </span>
          </div>

          {selectedLogs.length === 0 ? (
            <p className="text-center text-gray-400 text-sm py-6">No activity logged</p>
          ) : (
            <div className="space-y-2">
              {selectedLogs.map(log => (
                <div key={log.id} className="flex items-center gap-3 p-3 bg-gray-50 dark:bg-gray-700 rounded-xl">
                  <span className="text-xl">{getIcon(log.type)}</span>
                  <div className="flex-1 min-w-0">
                    <div className="font-medium capitalize text-sm dark:text-white">{log.type}</div>
                    <div className="text-xs text-gray-500 dark:text-gray-400 truncate">
                      {[
                        log.subType?.replace(/_/g, " "),
                        log.amount ? `${log.amount}ml` : null,
                        log.notes,
                      ].filter(Boolean).join(" · ")}
                    </div>
                  </div>
                  <div className="text-xs text-gray-400 flex-shrink-0">
                    {fmtTime(log.loggedAt)}
                  </div>
                </div>
              ))}
            </div>
          )}
        </div>
      )}
    </div>
  );
}