From 3a32fd8c4b575337a35d40e08695072a1478be29 Mon Sep 17 00:00:00 2001
From: KeshavAnandCode <keshavanand.dev@gmail.com>
Date: Fri, 15 May 2026 18:46:57 -0500
Subject: [PATCH] transpiler, errors

---
 .../foreignthon/src/foreignthon/errors.py     | 55 ++++++++++++
 .../foreignthon/src/foreignthon/transpiler.py | 83 +++++++++++++++++++
 2 files changed, 138 insertions(+)

diff --git a/packages/foreignthon/src/foreignthon/errors.py b/packages/foreignthon/src/foreignthon/errors.py
index e69de29..7f88d5a 100644
--- a/packages/foreignthon/src/foreignthon/errors.py
+++ b/packages/foreignthon/src/foreignthon/errors.py
@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+import sys
+import traceback
+
+from .pack import load_pack, PackNotFoundError
+
+_active_lang: str | None = None
+
+
+def activate(lang_code: str) -> None:
+    """Install the bilingual error hook for the given language."""
+    global _active_lang
+    _active_lang = lang_code
+    sys.excepthook = _bilingual_hook
+
+
+def deactivate() -> None:
+    """Restore the default Python error hook."""
+    global _active_lang
+    _active_lang = None
+    sys.excepthook = sys.__excepthook__
+
+
+def _bilingual_hook(exc_type, exc_value, exc_tb) -> None:
+    """
+    Print errors in foreign language first, English below.
+
+    [ES] ErrorDeValor: el argumento debe ser un número entero
+    [EN] ValueError: argument must be an integer
+         Traceback ...
+    """
+    try:
+        pack = load_pack(_active_lang)
+        error_messages = pack.get("error_messages", {})
+        exceptions = pack.get("exceptions", {})
+
+        # Reverse exceptions map: English name → foreign name
+        en_to_foreign = {v: k for k, v in exceptions.items()}
+
+        en_name = exc_type.__name__
+        foreign_name = en_to_foreign.get(en_name, en_name)
+        foreign_msg = error_messages.get(en_name, str(exc_value))
+        lang_code = pack["meta"]["code"].upper()
+
+        print(f"[{lang_code}] {foreign_name}: {foreign_msg}", file=sys.stderr)
+        print(f"[EN] {en_name}: {exc_value}", file=sys.stderr)
+        print(file=sys.stderr)
+
+    except (PackNotFoundError, Exception):
+        # If anything goes wrong with translation, fall back silently
+        pass
+
+    # Always print the standard traceback at the end
+    traceback.print_exception(exc_type, exc_value, exc_tb)
diff --git a/packages/foreignthon/src/foreignthon/transpiler.py b/packages/foreignthon/src/foreignthon/transpiler.py
index e69de29..9409448 100644
--- a/packages/foreignthon/src/foreignthon/transpiler.py
+++ b/packages/foreignthon/src/foreignthon/transpiler.py
@@ -0,0 +1,83 @@
+from __future__ import annotations
+
+import io
+import tokenize
+from pathlib import Path
+
+from .pack import load_pack
+
+
+def transpile(source: str, lang_code: str) -> str:
+    """
+    Transpile foreign-language Python source to standard Python.
+    Uses the tokenizer so strings and comments are never touched.
+    """
+    pack = load_pack(lang_code)
+
+    # Build a single flat lookup: foreign token -> English token
+    mapping: dict[str, str] = {}
+    mapping.update(pack["keywords"])
+    mapping.update(pack["builtins"])
+    mapping.update(pack["exceptions"])
+    mapping.update(pack["stdlib"])
+
+    tokens_in = tokenize.generate_tokens(io.StringIO(source).readline)
+    result: list[str] = []
+
+    prev_end = (1, 0)
+
+    for tok in tokens_in:
+        tok_type, tok_string, tok_start, tok_end, _ = tok
+
+        # Preserve original whitespace/indentation between tokens
+        start_row, start_col = tok_start
+        end_row, end_col = prev_end
+
+        if start_row == end_row:
+            result.append(" " * (start_col - end_col))
+        else:
+            result.append("\n" * (start_row - end_row))
+            result.append(" " * start_col)
+
+        # Only swap NAME tokens — leaves strings, comments, ops untouched
+        if tok_type == tokenize.NAME and tok_string in mapping:
+            result.append(mapping[tok_string])
+        else:
+            result.append(tok_string)
+
+        prev_end = tok_end
+
+    return "".join(result)
+
+
+def transpile_file(path: Path) -> str:
+    """
+    Detect language from file extension (.es.py → es),
+    read the file, and return transpiled Python source.
+    """
+    lang_code = _detect_lang(path)
+    source = path.read_text(encoding="utf-8")
+
+    # Allow shebang-style override: # foreignthon: fr
+    lang_code = _check_shebang(source, lang_code)
+
+    return transpile(source, lang_code)
+
+
+def _detect_lang(path: Path) -> str:
+    """Extract lang code from extension, e.g. script.es.py → es."""
+    suffixes = path.suffixes  # e.g. ['.es', '.py']
+    if len(suffixes) >= 2 and suffixes[-1] == ".py":
+        return suffixes[-2].lstrip(".")
+    raise ValueError(
+        f"Cannot detect language from filename '{path.name}'. "
+        "Expected format: script.<lang>.py (e.g. script.es.py)"
+    )
+
+
+def _check_shebang(source: str, default: str) -> str:
+    """Check first line for # foreignthon: <lang> override."""
+    first_line = source.splitlines()[0] if source else ""
+    if first_line.startswith("# foreignthon:"):
+        return first_line.split(":", 1)[1].strip()
+    return default