src/lib/editor/nli/executors.ts

/**
 * NLI Tool Call Executors — Convert tool call payloads into EditorEventBus dispatch calls.
 */

import type { SubtitleData, EditorEventType } from "../event-bus";
import { tcToMs } from "../validation";
import type { NliToolCall } from "./engine";

export interface EventDispatch {
  type: EditorEventType;
  target: number;
  payload: Record<string, unknown>;
}

export interface ExecutionResult {
  events: EventDispatch[];
  summary: string;
  affectedCount: number;
}

function msToTimecode(ms: number, fps: number): string {
  const totalSec = Math.max(0, ms / 1000);
  const h = Math.floor(totalSec / 3600);
  const m = Math.floor((totalSec % 3600) / 60);
  const s = Math.floor(totalSec % 60);
  const f = Math.floor((totalSec % 1) * fps);
  return `${String(h).padStart(2, "0")}:${String(m).padStart(2, "0")}:${String(s).padStart(2, "0")}:${String(f).padStart(2, "0")}`;
}

export function executeToolCall(
  toolCall: NliToolCall,
  subtitles: SubtitleData[],
  fps: number,
): ExecutionResult {
  switch (toolCall.toolName) {
    case "shift_timecodes":
      return executeShiftTimecodes(toolCall.input, subtitles, fps);
    case "convert_fps":
      return executeConvertFps(toolCall.input, subtitles, fps);
    case "find_and_replace":
      return executeFindAndReplace(toolCall.input, subtitles);
    case "bulk_delete":
      return executeBulkDelete(toolCall.input, subtitles);
    case "edit_subtitles":
      return executeEditSubtitles(toolCall.input);
    case "set_speakers":
      return executeSetSpeakers(toolCall.input);
    default:
      return { events: [], summary: `Unknown tool: ${toolCall.toolName}`, affectedCount: 0 };
  }
}

function executeShiftTimecodes(
  input: Record<string, unknown>,
  subtitles: SubtitleData[],
  fps: number,
): ExecutionResult {
  const offsetFrames = (input.offset_frames as number) || 0;
  const offsetMs = (input.offset_ms as number) || Math.round((offsetFrames / fps) * 1000);
  const startIdx = (input.start_index as number) ?? 0;
  const endIdx = (input.end_index as number) ?? subtitles.length - 1;

  const edits: Array<{ index: number; field: string; value: string }> = [];

  for (let i = startIdx; i <= endIdx && i < subtitles.length; i++) {
    const sub = subtitles[i];
    const newTcIn = msToTimecode(Math.max(0, tcToMs(sub.tcIn, fps) + offsetMs), fps);
    const newTcOut = msToTimecode(Math.max(0, tcToMs(sub.tcOut, fps) + offsetMs), fps);
    edits.push({ index: i, field: "tcIn", value: newTcIn });
    edits.push({ index: i, field: "tcOut", value: newTcOut });
  }

  const count = endIdx - startIdx + 1;
  return {
    events: [{
      type: "batchEdit",
      target: 0,
      payload: { edits },
    }],
    summary: `Shift ${count} subtitle${count !== 1 ? "s" : ""} by ${offsetFrames ? `${offsetFrames} frames` : `${offsetMs}ms`}`,
    affectedCount: count,
  };
}

function executeConvertFps(
  input: Record<string, unknown>,
  subtitles: SubtitleData[],
  fps: number,
): ExecutionResult {
  const fromFps = input.from_fps as number;
  const toFps = input.to_fps as number;

  const edits: Array<{ index: number; field: string; value: string }> = [];

  for (let i = 0; i < subtitles.length; i++) {
    const sub = subtitles[i];
    const tcInMs = tcToMs(sub.tcIn, fromFps);
    const tcOutMs = tcToMs(sub.tcOut, fromFps);
    edits.push({ index: i, field: "tcIn", value: msToTimecode(tcInMs, toFps) });
    edits.push({ index: i, field: "tcOut", value: msToTimecode(tcOutMs, toFps) });
  }

  return {
    events: [{
      type: "batchEdit",
      target: 0,
      payload: { edits },
    }],
    summary: `Convert ${subtitles.length} subtitles from ${fromFps} to ${toFps} FPS`,
    affectedCount: subtitles.length,
  };
}

function executeFindAndReplace(
  input: Record<string, unknown>,
  subtitles: SubtitleData[],
): ExecutionResult {
  const findStr = input.find as string;
  const replaceStr = input.replace as string;
  const isRegex = (input.is_regex as boolean) || false;
  const caseSensitive = (input.case_sensitive as boolean) ?? true;
  const field = (input.field as string) || "text";

  const flags = caseSensitive ? "g" : "gi";
  const pattern = isRegex ? new RegExp(findStr, flags) : new RegExp(findStr.replace(/[.*+?^${}()|[\]\\]/g, "\\$&"), flags);

  const edits: Array<{ index: number; field: string; value: string }> = [];

  for (let i = 0; i < subtitles.length; i++) {
    const sub = subtitles[i];
    const original = field === "speaker" ? sub.speaker : sub.text;
    const replaced = original.replace(pattern, replaceStr);
    if (replaced !== original) {
      edits.push({ index: i, field, value: replaced });
    }
  }

  return {
    events: edits.length > 0
      ? [{
          type: "batchEdit",
          target: 0,
          payload: { edits },
        }]
      : [],
    summary: edits.length > 0
      ? `Replaced "${findStr}" → "${replaceStr}" in ${edits.length} subtitle${edits.length !== 1 ? "s" : ""}`
      : `No matches found for "${findStr}"`,
    affectedCount: edits.length,
  };
}

function executeBulkDelete(
  input: Record<string, unknown>,
  subtitles: SubtitleData[],
): ExecutionResult {
  let indices: number[] = [];

  if (input.indices) {
    indices = (input.indices as number[]).filter((i) => i >= 0 && i < subtitles.length);
  }
  if (input.delete_empty) {
    for (let i = 0; i < subtitles.length; i++) {
      if (!subtitles[i].text.trim() && !indices.includes(i)) {
        indices.push(i);
      }
    }
  }

  // Sort descending so deletions don't shift indices
  indices.sort((a, b) => b - a);

  const events: EventDispatch[] = indices.map((i) => ({
    type: "deleteSubtitle" as const,
    target: i,
    payload: {},
  }));

  return {
    events,
    summary: `Delete ${indices.length} subtitle${indices.length !== 1 ? "s" : ""}`,
    affectedCount: indices.length,
  };
}

function executeEditSubtitles(input: Record<string, unknown>): ExecutionResult {
  const edits = input.edits as Array<{
    index: number;
    new_text: string;
    reason?: string;
  }>;

  if (!edits || edits.length === 0) {
    return { events: [], summary: "No edits to apply", affectedCount: 0 };
  }

  const batchEdits = edits.map((e) => ({
    index: e.index,
    field: "text",
    value: e.new_text,
  }));

  return {
    events: [{
      type: "batchEdit",
      target: 0,
      payload: { edits: batchEdits },
    }],
    summary: `Edit text in ${edits.length} subtitle${edits.length !== 1 ? "s" : ""}`,
    affectedCount: edits.length,
  };
}

function executeSetSpeakers(input: Record<string, unknown>): ExecutionResult {
  const assignments = input.assignments as Array<{
    index: number;
    speaker: string;
  }>;

  if (!assignments || assignments.length === 0) {
    return { events: [], summary: "No speaker changes", affectedCount: 0 };
  }

  const batchEdits = assignments.map((a) => ({
    index: a.index,
    field: "speaker",
    value: a.speaker,
  }));

  return {
    events: [{
      type: "batchEdit",
      target: 0,
      payload: { edits: batchEdits },
    }],
    summary: `Set speakers for ${assignments.length} subtitle${assignments.length !== 1 ? "s" : ""}`,
    affectedCount: assignments.length,
  };
}