param(
  [string]$DocumentPath = (Join-Path $PSScriptRoot "..\http-client-app-plan.md"),
  [string[]]$DisabledKeywords = @(
    "<<<<<<<",
    ">>>>>>>",
    "TODO_BLOCKER",
    "FIXME_BLOCKER"
  )
)

$ErrorActionPreference = "Stop"

$resolvedDocument = Resolve-Path -LiteralPath $DocumentPath
$python = Get-Command python -ErrorAction SilentlyContinue
$usePyLauncher = $false

if (-not $python) {
  $python = Get-Command py -ErrorAction SilentlyContinue
  $usePyLauncher = $true
}

if (-not $python) {
  Write-Error "Python was not found. Install Python 3 or make the 'python'/'py' command available on PATH."
}

$checker = @'
import argparse
import json
import re
import sys
from pathlib import Path


def line_col(text, offset):
    line = text.count("\n", 0, offset) + 1
    last_newline = text.rfind("\n", 0, offset)
    column = offset + 1 if last_newline == -1 else offset - last_newline
    return line, column


def check_code_fences(text):
    errors = []
    fence_pattern = re.compile(r"^[ \t]*```", re.MULTILINE)
    matches = list(fence_pattern.finditer(text))
    if len(matches) % 2 != 0:
        line, _ = line_col(text, matches[-1].start())
        errors.append(f"Unbalanced fenced code block near line {line}.")
    return errors


def check_json_blocks(text):
    errors = []
    block_pattern = re.compile(r"^[ \t]*```json[^\n]*\n(.*?)(?:\n^[ \t]*```[ \t]*$)", re.MULTILINE | re.DOTALL)
    for index, match in enumerate(block_pattern.finditer(text), start=1):
        raw_json = match.group(1)
        try:
            json.loads(raw_json)
        except json.JSONDecodeError as exc:
            start_line, _ = line_col(text, match.start(1))
            errors.append(
                f"Invalid JSON code block #{index} at line {start_line + exc.lineno - 1}, "
                f"column {exc.colno}: {exc.msg}."
            )
    return errors


def is_table_separator(line):
    stripped = line.strip()
    if "|" not in stripped:
        return False
    cells = [cell.strip() for cell in stripped.strip("|").split("|")]
    return bool(cells) and all(re.fullmatch(r":?-{3,}:?", cell or "") for cell in cells)


def pipe_count(line):
    stripped = line.strip()
    return stripped.count("|")


def check_tables(text):
    errors = []
    lines = text.splitlines()
    in_fence = False
    for index, line in enumerate(lines):
        if re.match(r"^[ \t]*```", line):
            in_fence = not in_fence
            continue
        if in_fence or not is_table_separator(line):
            continue

        table_lines = []
        cursor = index - 1
        while cursor >= 0 and "|" in lines[cursor]:
            table_lines.insert(0, (cursor + 1, lines[cursor]))
            cursor -= 1
        table_lines.append((index + 1, line))
        cursor = index + 1
        while cursor < len(lines) and "|" in lines[cursor]:
            table_lines.append((cursor + 1, lines[cursor]))
            cursor += 1

        counts = {pipe_count(table_line) for _, table_line in table_lines}
        if len(counts) > 1:
            first_line = table_lines[0][0]
            errors.append(f"Markdown table pipe count mismatch near line {first_line}.")
    return errors


def check_disabled_keywords(text, keywords):
    errors = []
    for keyword in keywords:
        if not keyword:
            continue
        offset = text.find(keyword)
        if offset != -1:
            line, column = line_col(text, offset)
            errors.append(f"Disabled keyword '{keyword}' found at line {line}, column {column}.")
    return errors


def main():
    parser = argparse.ArgumentParser(description="Verify Markdown planning document structure.")
    parser.add_argument("document")
    parser.add_argument("--keyword", action="append", default=[])
    args = parser.parse_args()

    document = Path(args.document)
    text = document.read_text(encoding="utf-8-sig")

    errors = []
    errors.extend(check_code_fences(text))
    errors.extend(check_json_blocks(text))
    errors.extend(check_tables(text))
    errors.extend(check_disabled_keywords(text, args.keyword))

    if errors:
        print(f"Documentation verification failed for {document}:")
        for error in errors:
            print(f" - {error}")
        return 1

    print(f"Documentation verification passed for {document}.")
    return 0


if __name__ == "__main__":
    sys.exit(main())
'@

$tempChecker = Join-Path ([System.IO.Path]::GetTempPath()) ("verify-docs-{0}.py" -f ([System.Guid]::NewGuid().ToString("N")))

try {
  Set-Content -LiteralPath $tempChecker -Value $checker -Encoding UTF8

  $arguments = @()
  if ($usePyLauncher) {
    $arguments += "-3"
  }
  $arguments += @($tempChecker, $resolvedDocument.Path)
  foreach ($keyword in $DisabledKeywords) {
    $arguments += @("--keyword", $keyword)
  }

  & $python.Source @arguments
  exit $LASTEXITCODE
}
finally {
  if (Test-Path -LiteralPath $tempChecker) {
    Remove-Item -LiteralPath $tempChecker -Force
  }
}