"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { MusicNotes, Pause, Play, Trash, UploadSimple, Warning } from "@phosphor-icons/react";

import { Panel, Switch } from "@/components/ui";
import { Waveform, useAudioPeaks } from "@/components/waveform";
import { formatClock } from "@/lib/presets";

export interface ReferenceState {
  file: File | null;
  filename: string | null;
  status: "empty" | "uploading" | "ready" | "failed";
  error: string | null;
  /** Seconds into the file to start transcribing. */
  start: number;
  /** Seconds to transcribe, or null for the whole thing. */
  duration: number | null;
}

export const EMPTY_REFERENCE: ReferenceState = {
  file: null,
  filename: null,
  status: "empty",
  error: null,
  start: 0,
  duration: null,
};

const ACCEPTED = ".wav,.mp3,.flac,.ogg,.m4a,.aac,.opus,.webm";

export function ReferenceDrop({
  state,
  onChange,
}: {
  state: ReferenceState;
  onChange: (next: ReferenceState) => void;
}) {
  const inputRef = useRef<HTMLInputElement>(null);
  const [dragging, setDragging] = useState(false);
  const { peaks, duration, failed } = useAudioPeaks(state.file, 420);
  const preview = useLocalPlayback(state.file);

  const accept = useCallback(
    async (file: File) => {
      onChange({ file, filename: null, status: "uploading", error: null, start: 0, duration: null });

      const form = new FormData();
      form.append("file", file);

      try {
        const res = await fetch("/api/upload", { method: "POST", body: form });
        const body = await res.json();
        if (!res.ok) throw new Error(body.error ?? "Upload failed");
        onChange({ file, filename: body.filename, status: "ready", error: null, start: 0, duration: null });
      } catch (error) {
        onChange({
          file,
          filename: null,
          status: "failed",
          error: error instanceof Error ? error.message : "Upload failed",
          start: 0,
          duration: null,
        });
      }
    },
    [onChange],
  );

  if (state.file) {
    return (
      <Panel
        title="Reference recording"
        hint="Transcribed to a melody score, then re-sung."
        aside={
          <button
            type="button"
            onClick={() => onChange(EMPTY_REFERENCE)}
            className="flex items-center gap-1.5 text-[12px] text-ink-faint transition-colors hover:text-alarm"
          >
            <Trash size={13} weight="bold" />
            Remove
          </button>
        }
      >
        <div className="flex items-start gap-3">
          <MusicNotes size={18} weight="fill" className="mt-0.5 shrink-0 text-citron" />
          <div className="min-w-0 flex-1">
            <p className="truncate text-[13px] text-ink">{state.file.name}</p>
            <p className="mt-0.5 font-mono text-[11.5px] text-ink-faint">
              {(state.file.size / 1024 / 1024).toFixed(1)} MB
              {duration > 0 ? `  ${formatClock(duration)}` : ""}
            </p>
          </div>
          <StatusBadge status={state.status} />
        </div>

        <div className="mt-3 rounded-console border border-line bg-void px-3 py-2.5">
          {failed ? (
            <p className="py-3 text-[12px] text-ink-faint">
              This browser could not decode the file for preview. ComfyUI will still read it.
            </p>
          ) : (
            <div className="flex items-center gap-3">
              {/*
                The second of the two circular play buttons, deliberately
                smaller than the dock's so the transport stays the primary one.
              */}
              <button
                type="button"
                onClick={preview.toggle}
                aria-label={preview.playing ? "Pause the reference" : "Play the reference"}
                className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-citron text-void transition-transform duration-150 active:scale-95"
              >
                {preview.playing ? (
                  <Pause size={12} weight="fill" />
                ) : (
                  <Play size={12} weight="fill" />
                )}
              </button>

              <div className="min-w-0 flex-1">
                <Waveform
                  peaks={peaks}
                  progress={preview.progress}
                  onSeek={preview.seek}
                  height={40}
                />
              </div>

              <span className="shrink-0 font-mono text-[11px] text-ink-faint">
                {formatClock(preview.position)} / {formatClock(preview.length || duration)}
              </span>
            </div>
          )}
        </div>

        {preview.error ? (
          <p className="mt-2 text-[12px] text-alarm">{preview.error}</p>
        ) : null}

        <div className="mt-3 border-t border-line pt-3">
          <Switch
            checked={state.duration !== null || state.start > 0}
            onChange={(on) =>
              onChange({
                ...state,
                start: 0,
                duration: on ? Math.min(120, Math.round(duration) || 120) : null,
              })
            }
            label="Transcribe only part of it"
          />
          <p className="mt-1 text-[11.5px] leading-snug text-ink-faint">
            SheetSage2 reads the whole file by default. A long or busy recording can
            contain a note it cannot place on its grid, which fails the render.
          </p>

          {state.duration !== null || state.start > 0 ? (
            <div className="mt-3 flex flex-wrap items-end gap-3">
              <label className="flex flex-col gap-1">
                <span className="text-[11px] tracking-[0.06em] text-ink-dim uppercase">From</span>
                <input
                  type="number"
                  min={0}
                  max={Math.max(0, Math.floor(duration))}
                  value={state.start}
                  onChange={(event) => {
                    const limit = duration > 0 ? Math.floor(duration) - 1 : Infinity;
                    const start = Math.min(limit, Math.max(0, Number(event.target.value)));
                    onChange({ ...state, start });
                  }}
                  className="h-8 w-24 rounded-console border border-line-strong bg-void px-2 font-mono text-[12px] text-ink"
                />
              </label>
              <label className="flex flex-col gap-1">
                <span className="text-[11px] tracking-[0.06em] text-ink-dim uppercase">
                  Seconds
                </span>
                <input
                  type="number"
                  min={1}
                  max={duration > 0 ? Math.ceil(duration) : undefined}
                  value={state.duration ?? 60}
                  onChange={(event) => {
                    const remaining = duration > 0 ? Math.ceil(duration) - state.start : Infinity;
                    const seconds = Math.min(remaining, Math.max(1, Number(event.target.value)));
                    onChange({ ...state, duration: seconds });
                  }}
                  className="h-8 w-24 rounded-console border border-line-strong bg-void px-2 font-mono text-[12px] text-ink"
                />
              </label>
              <p className="pb-1.5 font-mono text-[11.5px] text-ink-faint">
                {formatClock(state.start)} to{" "}
                {formatClock(state.start + (state.duration ?? 0))}
                {duration > 0 ? ` of ${formatClock(duration)}` : ""}
              </p>
            </div>
          ) : null}
        </div>

        {preview.url ? (
          <audio
            ref={preview.ref}
            src={preview.url}
            preload="metadata"
            onPlay={() => preview.setPlaying(true)}
            onPause={() => preview.setPlaying(false)}
            onTimeUpdate={(event) => preview.setPosition(event.currentTarget.currentTime)}
            onLoadedMetadata={(event) => {
              const value = event.currentTarget.duration;
              if (Number.isFinite(value) && value > 0) preview.setLength(value);
            }}
            onEnded={() => {
              preview.setPlaying(false);
              preview.setPosition(0);
            }}
            onError={() => preview.setError("This browser will not play that file.")}
          />
        ) : null}

        {state.error ? (
          <p className="mt-2 flex items-start gap-1.5 text-[12px] text-alarm">
            <Warning size={13} weight="fill" className="mt-0.5 shrink-0" />
            {state.error}
          </p>
        ) : null}
      </Panel>
    );
  }

  return (
    <Panel title="Reference recording" hint="Optional. Keeps the tune, changes everything else.">
      <div
        onDragOver={(event) => {
          event.preventDefault();
          setDragging(true);
        }}
        onDragLeave={() => setDragging(false)}
        onDrop={(event) => {
          event.preventDefault();
          setDragging(false);
          const file = event.dataTransfer.files?.[0];
          if (file) void accept(file);
        }}
        className={`flex flex-col items-center justify-center rounded-console border border-dashed px-6 py-9 text-center transition-colors duration-150 ${
          dragging ? "border-citron bg-citron/5" : "border-line-strong bg-void"
        }`}
      >
        <UploadSimple size={20} weight="bold" className={dragging ? "text-citron" : "text-ink-faint"} />
        <p className="mt-3 text-[13px] text-ink">Drop a song here</p>
        <p className="mt-1 max-w-[42ch] text-[12px] leading-snug text-ink-faint">
          SheetSage2 reads the melody into a score. YuE2 then performs your lyrics over that melody
          in the style you wrote.
        </p>
        <button
          type="button"
          onClick={() => inputRef.current?.click()}
          className="mt-4 h-8 rounded-console border border-line-strong px-3 text-[12.5px] text-ink transition-colors hover:border-ink-faint hover:bg-raised"
        >
          Choose a file
        </button>
        <input
          ref={inputRef}
          type="file"
          accept={ACCEPTED}
          className="hidden"
          onChange={(event) => {
            const file = event.target.files?.[0];
            if (file) void accept(file);
            event.target.value = "";
          }}
        />
      </div>
    </Panel>
  );
}

function StatusBadge({ status }: { status: ReferenceState["status"] }) {
  if (status === "uploading") {
    return (
      <span className="shrink-0 rounded-console border border-line-strong px-2 py-0.5 font-mono text-[11px] text-ink-dim">
        sending
      </span>
    );
  }
  if (status === "ready") {
    return (
      <span className="shrink-0 rounded-console border border-citron/40 bg-citron/10 px-2 py-0.5 font-mono text-[11px] text-citron">
        on the box
      </span>
    );
  }
  if (status === "failed") {
    return (
      <span className="shrink-0 rounded-console border border-alarm/40 bg-alarm/10 px-2 py-0.5 font-mono text-[11px] text-alarm">
        failed
      </span>
    );
  }
  return null;
}


/**
 * Plays the picked file straight from memory, before it ever leaves the
 * browser. Hearing the reference matters: it is what decides the melody the
 * model will sing, so uploading one blind is a bad way to work.
 */
function useLocalPlayback(file: File | null) {
  const ref = useRef<HTMLAudioElement>(null);
  const [url, setUrl] = useState<string | null>(null);
  const [playing, setPlaying] = useState(false);
  const [position, setPosition] = useState(0);
  const [length, setLength] = useState(0);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!file) {
      setUrl(null);
      return;
    }
    const objectUrl = URL.createObjectURL(file);
    setUrl(objectUrl);
    setPlaying(false);
    setPosition(0);
    setLength(0);
    setError(null);
    // An object URL pins the file in memory until it is released.
    return () => URL.revokeObjectURL(objectUrl);
  }, [file]);

  const toggle = () => {
    const element = ref.current;
    if (!element) return;
    if (!element.paused) {
      element.pause();
      return;
    }
    element.play().catch(() => setError("This browser will not play that file."));
  };

  const seek = (ratio: number) => {
    const element = ref.current;
    if (!element || !length) return;
    element.currentTime = ratio * length;
    setPosition(ratio * length);
  };

  return {
    ref,
    url,
    playing,
    position,
    length,
    error,
    progress: length > 0 ? Math.min(1, position / length) : 0,
    toggle,
    seek,
    setPlaying,
    setPosition,
    setLength,
    setError,
  };
}