import {
  constantTempoMidi,
  cropMidi,
  deleteNote,
  editNote,
  dropChannel,
  encodeMidi,
  exportMidiCsv,
  exportMidiJson,
  parseMidi,
  quantizeMidi,
  remapChannel,
  transposeMidi,
  type MidiDocument,
} from "./midi";

export type MidiOperation =
  | { kind: "transpose"; semitones: number }
  | { kind: "quantize"; grid: number }
  | { kind: "tempo"; bpm: number }
  | { kind: "crop"; start: number; end: number }
  | { kind: "remap-channel"; from: number; to: number }
  | { kind: "drop-channel"; channel: number }
  | {
      kind: "edit-note";
      onOrder: number;
      note: number;
      velocity: number;
      startTick: number;
      endTick: number;
    }
  | { kind: "delete-note"; onOrder: number };

export type MidiTask =
  | { kind: "parse"; name: string; bytes: ArrayBuffer }
  | { kind: "operation"; document: MidiDocument; operation: MidiOperation }
  | {
      kind: "export";
      document: MidiDocument;
      format: "midi" | "csv" | "json";
    };

export type MidiTaskResult =
  | { kind: "document"; document: MidiDocument }
  | { kind: "bytes"; bytes: ArrayBuffer; mimeType: string }
  | { kind: "text"; text: string; mimeType: string };

/** Pure task entry point shared by the module worker and test fallback. */
export function executeMidiTask(task: MidiTask): MidiTaskResult {
  if (task.kind === "parse")
    return {
      kind: "document",
      document: parseMidi(task.name, new Uint8Array(task.bytes)),
    };
  if (task.kind === "operation") {
    const { document, operation } = task;
    const next =
      operation.kind === "transpose"
        ? transposeMidi(document, operation.semitones)
        : operation.kind === "quantize"
          ? quantizeMidi(document, operation.grid)
          : operation.kind === "tempo"
            ? constantTempoMidi(document, operation.bpm)
            : operation.kind === "crop"
              ? cropMidi(document, operation.start, operation.end)
              : operation.kind === "remap-channel"
                ? remapChannel(document, operation.from, operation.to)
                : operation.kind === "drop-channel"
                  ? dropChannel(document, operation.channel)
                  : operation.kind === "edit-note"
                    ? editNote(document, operation.onOrder, operation)
                    : deleteNote(document, operation.onOrder);
    return { kind: "document", document: next };
  }
  if (task.format === "midi") {
    const bytes = encodeMidi(task.document);
    return {
      kind: "bytes",
      bytes: Uint8Array.from(bytes).buffer,
      mimeType: "audio/midi",
    };
  }
  return {
    kind: "text",
    text:
      task.format === "csv"
        ? exportMidiCsv(task.document)
        : exportMidiJson(task.document),
    mimeType: task.format === "csv" ? "text/csv" : "application/json",
  };
}