"use client";

import { NoteEditor } from "@/components/note-editor";
import { ScoreViews } from "@/components/tab-score";
import { Alert, AlertDescription, AlertTitle } from "@/components/ui/alert";
import { Button } from "@/components/ui/button";
import { ToggleGroup, ToggleGroupItem } from "@/components/ui/toggle-group";
import type { FingeringSystem } from "@/lib/fingering";
import { SAMPLES } from "@/lib/samples";
import { blankScore, type Score } from "@/lib/score";
import { Loader2, Music2, Upload } from "lucide-react";
import { useEffect, useId, useState } from "react";

type Status = "empty" | "loading" | "ready" | "error";

type RecognizerInfo = {
  available: boolean;
  name: string;
  detail: string;
};

export function Converter() {
  const inputId = useId();
  const [score, setScore] = useState<Score | null>(null);
  const [system, setSystem] = useState<FingeringSystem>("baroque");
  const [status, setStatus] = useState<Status>("empty");
  const [error, setError] = useState<string | null>(null);
  const [warnings, setWarnings] = useState<string[]>([]);
  const [recognizer, setRecognizer] = useState<RecognizerInfo | null>(null);
  const [dragOver, setDragOver] = useState(false);

  useEffect(() => {
    let cancelled = false;
    fetch("/api/recognize")
      .then((response) => response.json())
      .then((info: RecognizerInfo) => {
        if (!cancelled) setRecognizer(info);
      })
      .catch(() => {
        if (!cancelled) {
          setRecognizer({
            available: false,
            name: "oemer",
            detail: "Could not check the local reader. Samples and the editor still work.",
          });
        }
      });
    return () => {
      cancelled = true;
    };
  }, []);

  function loadScore(next: Score) {
    setScore(structuredClone(next));
    setWarnings([]);
    setError(null);
    setStatus("ready");
  }

  async function onFile(file: File) {
    setError(null);
    const allowed =
      ["image/png", "image/jpeg", "image/webp"].includes(file.type) ||
      /\.(png|jpe?g|webp)$/i.test(file.name);
    if (file.size === 0) {
      setError("That file is empty. No notes were invented.");
      setScore((current) => current ?? blankScore());
      setStatus("error");
      return;
    }
    if (!allowed) {
      setError("Use a PNG, JPG, or WEBP photo. That file is not one of those. No notes were invented.");
      setScore((current) => current ?? blankScore());
      setStatus("error");
      return;
    }
    if (file.size > 8 * 1024 * 1024) {
      setError("That image is over 8 MB. Crop the line or export a smaller JPEG.");
      setScore((current) => current ?? blankScore());
      setStatus("error");
      return;
    }

    setStatus("loading");
    try {
      const body = new FormData();
      body.set("image", file);
      const response = await fetch("/api/recognize", { method: "POST", body });
      const data = (await response.json()) as {
        error?: string;
        score?: Score;
        warnings?: string[];
      };
      if (!response.ok || data.error || !data.score) {
        setError(data.error ?? "This image could not be read. No notes were invented.");
        setWarnings([]);
        setScore((current) => current ?? blankScore());
        setStatus("error");
        return;
      }
      setScore(data.score);
      setWarnings(data.warnings ?? []);
      setStatus("ready");
    } catch {
      setError("The reader did not answer. No notes were invented. You can still enter the line by hand.");
      setScore((current) => current ?? blankScore());
      setStatus("error");
    }
  }

  return (
    <div className="mx-auto flex w-full max-w-6xl flex-col gap-6 px-4 py-6 md:px-8 md:py-10">
      <header className="space-y-3">
        <p className="text-sm tracking-[0.16em] text-[#6a4328] uppercase">Soprano in C · concert pitch</p>
        <h1 className="font-heading text-4xl leading-tight md:text-5xl">Recorder Tab Converter</h1>
        <p className="max-w-2xl text-base leading-7 text-muted-foreground">
          Turn a lead melody into fingering tabs a soprano player can read: thumb and holes, the note
          name, and the rhythm, lined up in bars. Chords keep the top note. A second staff is ignored.
        </p>
      </header>

      <section
        className={`rounded-3xl bg-card p-4 ring-1 ring-foreground/10 md:p-6 ${dragOver ? "ring-2 ring-primary" : ""}`}
        onDragOver={(event) => {
          event.preventDefault();
          setDragOver(true);
        }}
        onDragLeave={() => setDragOver(false)}
        onDrop={(event) => {
          event.preventDefault();
          setDragOver(false);
          const file = event.dataTransfer.files[0];
          if (file) void onFile(file);
        }}
      >
        <div className="flex flex-col gap-4 md:flex-row md:items-center md:justify-between">
          <div className="space-y-1">
            <h2 className="font-heading text-2xl">Photo or scan</h2>
            <p className="max-w-xl text-sm leading-6 text-muted-foreground">
              {recognizer?.detail ?? "Checking the local reader…"}
            </p>
          </div>
          <div className="flex flex-wrap gap-2">
            <Button
              type="button"
              disabled={status === "loading"}
              nativeButton={false}
              render={<label htmlFor={inputId} />}
            >
              {status === "loading" ? <Loader2 className="animate-spin" /> : <Upload />}
              {status === "loading" ? "Reading the page" : "Choose image"}
            </Button>
            <input
              id={inputId}
              className="sr-only"
              type="file"
              accept="image/png,image/jpeg,image/webp,.png,.jpg,.jpeg,.webp"
              onChange={(event) => {
                const file = event.target.files?.[0];
                event.target.value = "";
                if (file) void onFile(file);
              }}
            />
          </div>
        </div>
        {status === "loading" ? (
          <p className="mt-4 text-sm text-muted-foreground" role="status">
            oemer is reading the page on this computer. A dense photo can take a few minutes. Nothing
            is uploaded.
          </p>
        ) : (
          <p className="mt-4 text-sm text-muted-foreground">
            Drop a PNG, JPG, or WEBP here, or open a sample below if you want to see the tabs before a
            photo works.
          </p>
        )}
      </section>

      {error ? (
        <Alert variant="destructive">
          <AlertTitle>The page was not read</AlertTitle>
          <AlertDescription>{error}</AlertDescription>
        </Alert>
      ) : null}

      {warnings.length > 0 ? (
        <Alert>
          <AlertTitle>What the reader kept</AlertTitle>
          <AlertDescription>
            <ul className="list-disc pl-4">
              {warnings.map((warning) => (
                <li key={warning}>{warning}</li>
              ))}
            </ul>
          </AlertDescription>
        </Alert>
      ) : null}

      <section className="grid gap-3 sm:grid-cols-2">
        {SAMPLES.map((sample) => (
          <button
            key={sample.id}
            type="button"
            onClick={() => loadScore(sample.score)}
            className="rounded-2xl bg-card p-4 text-left ring-1 ring-foreground/10 transition hover:ring-primary"
          >
            <span className="flex items-center gap-2 font-heading text-xl">
              <Music2 className="size-4 text-[#6a4328]" />
              {sample.score.title}
            </span>
            <span className="mt-2 block text-sm leading-6 text-muted-foreground">{sample.blurb}</span>
          </button>
        ))}
      </section>

      {score ? (
        <>
          <div className="flex flex-col gap-3 sm:flex-row sm:items-end sm:justify-between">
            <div>
              <h2 className="font-heading text-3xl">{score.title}</h2>
              <p className="mt-1 max-w-2xl text-sm leading-6 text-muted-foreground">{score.attribution}</p>
            </div>
            <div className="space-y-1">
              <p className="text-xs tracking-wide text-muted-foreground uppercase">Fingering</p>
              <ToggleGroup
                value={[system]}
                spacing={0}
                variant="outline"
                onValueChange={(values) => {
                  const picked = values[values.length - 1];
                  if (picked === "baroque" || picked === "german") setSystem(picked);
                }}
                aria-label="Fingering system"
              >
                <ToggleGroupItem value="baroque">Baroque</ToggleGroupItem>
                <ToggleGroupItem value="german">German</ToggleGroupItem>
              </ToggleGroup>
              <p className="max-w-sm text-xs leading-5 text-muted-foreground">
                Baroque is the Dolmetsch chart and the default. German only changes F, F♯, and B♭.
              </p>
            </div>
          </div>
          <div className="grid items-start gap-6 lg:grid-cols-[minmax(18rem,22rem)_minmax(0,1fr)]">
            <div className="order-2 space-y-3 lg:order-1 lg:sticky lg:top-4 lg:max-h-[calc(100vh-2rem)] lg:overflow-y-auto lg:pr-1">
              <h2 className="font-heading text-2xl">Note list</h2>
              <p className="text-sm leading-6 text-muted-foreground">
                Pitch, rest, and duration. Change anything the photo got wrong. The tabs follow this
                list, including the bar lines.
              </p>
              <NoteEditor score={score} onChange={setScore} />
            </div>
            <div className="order-1 min-w-0 lg:order-2">
              <ScoreViews score={score} system={system} />
            </div>
          </div>
        </>
      ) : (
        <div className="rounded-3xl border border-dashed border-foreground/15 px-4 py-10 text-center">
          <p className="font-heading text-2xl">No line loaded yet</p>
          <p className="mx-auto mt-2 max-w-md text-sm leading-6 text-muted-foreground">
            Open Twinkle or Ode to Joy to see fingerings and rhythm immediately, or start an empty
            bar and type the notes yourself.
          </p>
          <Button type="button" className="mt-4" variant="secondary" onClick={() => loadScore(blankScore())}>
            Start an empty line
          </Button>
        </div>
      )}
    </div>
  );
}