export interface EdlImportRow {
  outputName: string;
  sourceClip: string;
  timecodeStart: string;
  timecodeEnd: string;
  clipDuration: string;
  // Derived
  shotCode: string;
  exrOutput: string;
  // Action decided during preview
  action: "create" | "update" | "skip";
  existingShotId?: string;
}

/** Parse a single CSV line, handling quoted fields and escaped double-quotes. */
function parseCsvLine(line: string): string[] {
  const result: string[] = [];
  let current = "";
  let inQuotes = false;
  for (let i = 0; i < line.length; i++) {
    const ch = line[i];
    if (inQuotes) {
      if (ch === '"') {
        if (line[i + 1] === '"') { current += '"'; i++; } // escaped ""
        else { inQuotes = false; }
      } else {
        current += ch;
      }
    } else {
      if (ch === '"') {
        inQuotes = true;
      } else if (ch === ',') {
        result.push(current.trim());
        current = "";
      } else {
        current += ch;
      }
    }
  }
  result.push(current.trim());
  return result;
}

/**
 * Parse a VFX pull CSV into import rows.
 * Output Name format: {showId}_{episode}_{scene}_{shot}_BG01_TT_v001
 * shotCode = first 4 underscore-separated segments
 * exrOutput = {shotCode}_{sourceClip}
 */
export function parseEdlCsv(csvText: string): { rows: EdlImportRow[]; errors: string[] } {
  const lines = csvText.split(/\r?\n/).map((l) => l.trim()).filter(Boolean);
  if (lines.length < 2) return { rows: [], errors: ["CSV must have a header row and at least one data row"] };

  const rawHeaders = parseCsvLine(lines[0]).map((h) => h.toLowerCase());
  const col = (name: string) => rawHeaders.indexOf(name);

  const outNameIdx = col("output name");
  const srcClipIdx = col("source clip");
  const tcStartIdx = col("timecode start");
  const tcEndIdx   = col("timecode end");
  const durIdx     = col("duration");

  if (outNameIdx === -1 || srcClipIdx === -1) {
    return { rows: [], errors: ['CSV must contain "Output Name" and "Source Clip" columns'] };
  }

  const rows: EdlImportRow[] = [];
  const errors: string[] = [];

  for (let i = 1; i < lines.length; i++) {
    const cells = parseCsvLine(lines[i]);
    const get = (idx: number) => (idx !== -1 ? cells[idx] ?? "" : "");

    const outputName = get(outNameIdx);
    const sourceClip = get(srcClipIdx);
    if (!outputName) { errors.push(`Row ${i + 1}: empty Output Name — skipped`); continue; }

    const parts = outputName.split("_");
    if (parts.length < 4) {
      errors.push(`Row ${i + 1}: "${outputName}" — cannot parse shot code (need at least 4 segments)`);
      continue;
    }
    const shotCode = parts.slice(0, 4).join("_");
    const exrOutput = sourceClip ? `${shotCode}_${sourceClip}` : shotCode;

    rows.push({
      outputName,
      sourceClip,
      timecodeStart: get(tcStartIdx),
      timecodeEnd:   get(tcEndIdx),
      clipDuration:  get(durIdx),
      shotCode,
      exrOutput,
      action: "create",
    });
  }

  return { rows, errors };
}

// ── Picture Tracker CSV Parser ────────────────────────────────────────────────

export interface PictureTrackerRow {
  shotCode: string;
  seqTimecodeStart: string;
  seqTimecodeEnd: string;
  /** true when shotCode matched an existing shot in the project */
  exists: boolean;
}

/**
 * TC values exported by some tools contain invalid values like "aN:aN:aN:aN"
 * or "#ERROR!". Reject anything that doesn't look like HH:MM:SS:FF.
 */
function isValidTimecode(tc: string): boolean {
  return /^\d{2}:\d{2}:\d{2}[:;]\d{2}$/.test(tc.trim());
}

/**
 * Parse a picture tracker CSV.
 *
 * Expected header (col indices may vary, but we find by name):
 *   #, Thumbnail, Shot Name, TC In, TC Out, Duration, ...
 *
 * Only the FIRST TC In/Out for each unique Shot Name is used
 * (subsequent rows for the same shot are ignored).
 *
 * @param csvText       raw CSV text
 * @param existingCodes set of shotCodes already in the project
 */
export function parsePictureTrackerCsv(
  csvText: string,
  existingCodes: Set<string>
): { rows: PictureTrackerRow[]; errors: string[] } {
  const lines = csvText.split(/\r?\n/).map((l) => l.trim()).filter(Boolean);
  if (lines.length < 2) {
    return { rows: [], errors: ["CSV must have a header row and at least one data row"] };
  }

  const rawHeaders = parseCsvLine(lines[0]).map((h) => h.toLowerCase().trim());
  const col = (name: string) => rawHeaders.indexOf(name);

  const shotNameIdx = col("shot name");
  const tcInIdx     = col("tc in");
  const tcOutIdx    = col("tc out");

  if (shotNameIdx === -1) {
    return { rows: [], errors: ['CSV must contain a "Shot Name" column'] };
  }
  if (tcInIdx === -1 || tcOutIdx === -1) {
    return { rows: [], errors: ['CSV must contain "TC In" and "TC Out" columns'] };
  }

  const rows: PictureTrackerRow[] = [];
  const errors: string[] = [];
  const seen = new Set<string>();

  for (let i = 1; i < lines.length; i++) {
    const cells = parseCsvLine(lines[i]);
    const get = (idx: number) => (idx < cells.length ? cells[idx] ?? "" : "").trim();

    const shotCode = get(shotNameIdx);
    if (!shotCode) continue;

    // Only use the first occurrence per shot
    if (seen.has(shotCode)) continue;

    const tcIn  = get(tcInIdx);
    const tcOut = get(tcOutIdx);

    if (!isValidTimecode(tcIn) || !isValidTimecode(tcOut)) {
      errors.push(`Row ${i + 1} (${shotCode}): invalid timecode "${tcIn}" / "${tcOut}" — skipped`);
      continue;
    }

    seen.add(shotCode);
    rows.push({
      shotCode,
      seqTimecodeStart: tcIn,
      seqTimecodeEnd:   tcOut,
      exists: existingCodes.has(shotCode),
    });
  }

  return { rows, errors };
}

// ── Simple Shot CSV ──────────────────────────────────────────────────────────

export interface SimpleCsvRow {
  shotCode: string;
  seqTimecodeStart: string;
  seqTimecodeEnd: string;
  description: string;
  group: string;
  action: "create" | "update" | "skip";
}

/**
 * Parse a simple shot CSV: Shot Name, Time Code In, Time Code Out, Description.
 * Column names are matched case-insensitively with common aliases.
 * Timecodes are validated but not required.
 */
export function parseSimpleCsv(
  csvText: string,
  existingCodes: Set<string>
): { rows: SimpleCsvRow[]; errors: string[] } {
  const lines = csvText.split(/\r?\n/).map((l) => l.trim()).filter(Boolean);
  if (lines.length < 2) {
    return { rows: [], errors: ["CSV must have a header row and at least one data row"] };
  }

  const rawHeaders = parseCsvLine(lines[0]).map((h) => h.toLowerCase().trim());
  const col = (names: string[]) => {
    for (const name of names) {
      const idx = rawHeaders.indexOf(name);
      if (idx !== -1) return idx;
    }
    return -1;
  };

  const shotNameIdx = col(["shot name", "shot code", "shotcode", "shot", "name"]);
  const tcInIdx     = col(["time code in", "timecode in", "tc in", "tcin", "timecode start", "tc start"]);
  const tcOutIdx    = col(["time code out", "timecode out", "tc out", "tcout", "timecode end", "tc end"]);
  const descIdx     = col(["description", "desc", "notes", "note"]);
  const groupIdx    = col(["group", "shot group", "shotgroup", "group name"]);

  if (shotNameIdx === -1) {
    return { rows: [], errors: ['CSV must contain a "Shot Name" (or "Shot Code") column'] };
  }

  const rows: SimpleCsvRow[] = [];
  const errors: string[] = [];

  for (let i = 1; i < lines.length; i++) {
    const cells = parseCsvLine(lines[i]);
    const get = (idx: number) =>
      idx !== -1 && idx < cells.length ? (cells[idx] ?? "").trim() : "";

    const shotCode = get(shotNameIdx);
    if (!shotCode) { errors.push(`Row ${i + 1}: empty Shot Name — skipped`); continue; }

    const tcIn  = get(tcInIdx);
    const tcOut = get(tcOutIdx);

    if (tcIn && !isValidTimecode(tcIn)) {
      errors.push(`Row ${i + 1} (${shotCode}): invalid TC In "${tcIn}" — skipped`);
      continue;
    }
    if (tcOut && !isValidTimecode(tcOut)) {
      errors.push(`Row ${i + 1} (${shotCode}): invalid TC Out "${tcOut}" — skipped`);
      continue;
    }

    rows.push({
      shotCode,
      seqTimecodeStart: tcIn,
      seqTimecodeEnd:   tcOut,
      description:      get(descIdx),
      group:            get(groupIdx),
      action: existingCodes.has(shotCode) ? "update" : "create",
    });
  }

  return { rows, errors };
}

// ── Group Assignment CSV ──────────────────────────────────────────────────────

export interface GroupAssignRow {
  shotCode: string;
  groupName: string;
  exists: boolean;
}

/**
 * Parse a group-assignment CSV: Shot Name, Group.
 * Only shots that already exist in the project will be updated.
 */
export function parseGroupAssignCsv(
  csvText: string,
  existingCodes: Set<string>
): { rows: GroupAssignRow[]; errors: string[] } {
  const lines = csvText.split(/\r?\n/).map((l) => l.trim()).filter(Boolean);
  if (lines.length < 2) {
    return { rows: [], errors: ["CSV must have a header row and at least one data row"] };
  }

  const rawHeaders = parseCsvLine(lines[0]).map((h) => h.toLowerCase().trim());
  const col = (names: string[]) => {
    for (const name of names) {
      const idx = rawHeaders.indexOf(name);
      if (idx !== -1) return idx;
    }
    return -1;
  };

  const shotNameIdx = col(["shot name", "shot code", "shotcode", "shot", "name"]);
  const groupIdx    = col(["group", "shot group", "shotgroup", "group name"]);

  if (shotNameIdx === -1) {
    return { rows: [], errors: ['CSV must contain a "Shot Name" (or "Shot Code") column'] };
  }
  if (groupIdx === -1) {
    return { rows: [], errors: ['CSV must contain a "Group" column'] };
  }

  const rows: GroupAssignRow[] = [];
  const errors: string[] = [];
  const seen = new Set<string>();

  for (let i = 1; i < lines.length; i++) {
    const cells = parseCsvLine(lines[i]);
    const get = (idx: number) =>
      idx !== -1 && idx < cells.length ? (cells[idx] ?? "").trim() : "";

    const shotCode  = get(shotNameIdx);
    const groupName = get(groupIdx);
    if (!shotCode)  { errors.push(`Row ${i + 1}: empty Shot Name — skipped`); continue; }
    if (!groupName) { errors.push(`Row ${i + 1} (${shotCode}): empty Group — skipped`); continue; }
    if (seen.has(shotCode)) continue;
    seen.add(shotCode);

    rows.push({ shotCode, groupName, exists: existingCodes.has(shotCode) });
  }

  return { rows, errors };
}