"""
Code parser (tree-sitter).

Turns a Python source file into a list of *definitions* -- functions, classes,
and methods -- each with the exact source text and 1-indexed start/end lines.
Those line numbers are what make citations exact and un-hallucinatable later.

It handles the real-world cases that trip up naive parsing:
  - methods inside classes  (named "ClassName.method", type "method")
  - decorators              (@app.route etc. -> included in the chunk + lines)
  - nested functions        (found via full-tree recursion)
  - module-level imports     (collected into one "module" context chunk)

Run standalone to inspect a repo's definitions:
    python -m src.ingestion.parser path/to/repo_dir
"""
import tree_sitter_python as tspython
from tree_sitter import Language, Parser

_PY_LANGUAGE = Language(tspython.language())
_parser = Parser(_PY_LANGUAGE)

# Top-level nodes we fold into a per-file "module" chunk (imports + config).
_MODULE_CONTEXT_TYPES = {
    "import_statement",
    "import_from_statement",
    "expression_statement",  # top-level assignments / constants
}


def _node_text(src_bytes, node):
    return src_bytes[node.start_byte:node.end_byte].decode("utf-8", errors="ignore")


def _name_of(src_bytes, def_node):
    n = def_node.child_by_field_name("name")
    return _node_text(src_bytes, n) if n is not None else "<anonymous>"


def _unwrap(node):
    """
    If node is (or wraps) a function/class definition, return
    (def_node_for_naming, outer_node_for_range); else None.

    decorated_definition wraps the real def with its decorators, so we name
    from the inner def but take the code/line range from the outer node so the
    decorators are part of the chunk.
    """
    if node.type in ("function_definition", "class_definition"):
        return node, node
    if node.type == "decorated_definition":
        for child in node.children:
            if child.type in ("function_definition", "class_definition"):
                return child, node
    return None


def extract_definitions(rel_path, source):
    """Return a list of definition dicts for one file."""
    src_bytes = source.encode("utf-8")
    root = _parser.parse(src_bytes).root_node
    defs = []

    def emit(def_node, outer, parent_class):
        is_class = def_node.type == "class_definition"
        kind = "class" if is_class else ("method" if parent_class else "function")
        name = _name_of(src_bytes, def_node)
        full_name = f"{parent_class}.{name}" if parent_class else name
        defs.append({
            "file": rel_path,
            "type": kind,
            "name": full_name,
            "start_line": outer.start_point[0] + 1,
            "end_line": outer.end_point[0] + 1,
            "code": _node_text(src_bytes, outer),
        })
        return name if is_class else None

    def walk(node, parent_class):
        for child in node.children:
            info = _unwrap(child)
            if info:
                def_node, outer = info
                new_parent = emit(def_node, outer, parent_class)
                # descend into the body: a class's inner funcs become methods
                walk(def_node, new_parent)
            else:
                # not a definition -> keep descending to find nested defs
                walk(child, parent_class)

    walk(root, parent_class=None)

    # one "module" chunk per file: top-level imports + constants
    context_nodes = [c for c in root.children if c.type in _MODULE_CONTEXT_TYPES]
    if context_nodes:
        defs.append({
            "file": rel_path,
            "type": "module",
            "name": rel_path,
            "start_line": context_nodes[0].start_point[0] + 1,
            "end_line": context_nodes[-1].end_point[0] + 1,
            "code": "\n".join(_node_text(src_bytes, n) for n in context_nodes),
        })

    return defs


def parse_files(files):
    """Run extract_definitions over scanner output (list of file records)."""
    all_defs = []
    for f in files:
        all_defs.extend(extract_definitions(f["rel_path"], f["source"]))
    return all_defs


if __name__ == "__main__":
    import sys
    from src.ingestion.scanner import scan_python_files, scan_repo

    if len(sys.argv) < 2:
        print("usage: python -m src.ingestion.parser <repo.zip | repo_dir>")
        sys.exit(1)

    target = sys.argv[1]
    files = scan_repo(target)[0] if target.lower().endswith(".zip") else scan_python_files(target)

    defs = parse_files(files)
    print(f"Extracted {len(defs)} definitions from {len(files)} files:\n")
    for d in defs:
        print(f"  [{d['type']:8}] {d['file']}:{d['start_line']}-{d['end_line']}  {d['name']}")