#!/usr/bin/env python3
"""tsq.py — structural search for the judged leg (tree-sitter).

The judge's investigation instrument: query source STRUCTURE (call
nodes, not strings), get back matches whose spans ARE verbatim quotes —
so every citation is discovered, not composed. grep matches comments and
near-misses; this matches code.

Queries (v1):
  tsq.py call <name>            every call whose target is <name>
                                (bare `plug`, or dotted `System.get_env`,
                                or rightmost match `get_env`)
  tsq.py --scm <query.scm>      raw tree-sitter query (escape hatch)

Options:
  --repo DIR      repository root (default .)
  --in PREFIX     limit to paths under PREFIX (repeatable)
  --lang elixir   grammar (only elixir today)
  --json          records with byte spans instead of grep-style lines

Output (default): file:line: first-line-of-match
Output (--json):  {"file","line","start_byte","end_byte","text"} per match
                  — "text" is the exact source span: paste it as a quote
                  and the instrument's verification will pass by
                  construction.

Deps: pip install tree-sitter tree-sitter-elixir
"""

import argparse
import json
import os
import re
import sys

import tree_sitter
import tree_sitter_elixir

LANGS = {"elixir": tree_sitter.Language(tree_sitter_elixir.language())}


def code_files(repo, prefixes):
    out = []
    for base, dirs, names in os.walk(repo):
        rel_base = os.path.relpath(base, repo)
        top = rel_base.split(os.sep)[0]
        if top in {".git", "deps", "_build", "node_modules", "assets", "docs"}:
            dirs[:] = []
            continue
        for n in names:
            if not (n.endswith(".ex") or n.endswith(".exs")):
                continue
            rel = os.path.normpath(os.path.join(rel_base, n)).replace(os.sep, "/")
            if prefixes and not any(rel.startswith(p) for p in prefixes):
                continue
            out.append(rel)
    return sorted(out)


def call_target(src, node):
    """The textual target of a call node: `plug`, `System.get_env`, …"""
    if not node.children:
        return None
    t = node.children[0]
    if t.type == "identifier":
        return src[t.start_byte : t.end_byte].decode(errors="replace")
    if t.type == "dot":
        return src[t.start_byte : t.end_byte].decode(errors="replace")
    return None


def match_call(target, name):
    if target is None:
        return False
    if target == name:
        return True
    # rightmost-segment match: `get_env` finds `System.get_env`
    return "." in target and target.rsplit(".", 1)[-1] == name


def find_calls(src, root, name):
    out = []
    stack = [root]
    while stack:
        n = stack.pop()
        if n.type == "call" and match_call(call_target(src, n), name):
            out.append(n)
        stack.extend(reversed(n.children))
    return out


def run_scm(lang, src, root, scm):
    """One node per MATCH (the widest captured span), not per capture —
    a query with helper captures (@f inside @m) still counts each
    logical match once, and the cited span is the enclosing one."""
    query = tree_sitter.Query(lang, scm)
    cursor = tree_sitter.QueryCursor(query)
    out = []
    for _match_id, captures in cursor.matches(root):
        nodes = [n for ns in captures.values() for n in ns]
        if nodes:
            out.append(max(nodes, key=lambda n: n.end_byte - n.start_byte))
    return out


def textual_hits(repo, prefixes, name):
    """Occurrences of `name` as TEXT in the scoped files — the cross-check
    behind absence claims (0 structural + textual hits = not citable)."""
    frag = name.rsplit(".", 1)[-1].encode()
    n = 0
    for rel in code_files(repo, prefixes):
        try:
            n += open(os.path.join(repo, rel), "rb").read().count(frag)
        except OSError:
            continue
    return n


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("kind", nargs="?", choices=["call"])
    ap.add_argument("name", nargs="?")
    ap.add_argument("--scm")
    ap.add_argument("--repo", default=".")
    ap.add_argument("--in", dest="prefixes", action="append", default=[])
    ap.add_argument("--lang", default="elixir")
    ap.add_argument("--json", action="store_true")
    args = ap.parse_args()

    if not args.scm and not (args.kind and args.name):
        ap.error("either `call <name>` or --scm <file>")

    lang = LANGS[args.lang]
    parser = tree_sitter.Parser(lang)
    scm = open(args.scm).read() if args.scm else None

    records = []
    for rel in code_files(args.repo, args.prefixes):
        try:
            src = open(os.path.join(args.repo, rel), "rb").read()
        except OSError:
            continue
        root = parser.parse(src).root_node
        nodes = run_scm(lang, src, root, scm) if scm else find_calls(src, root, args.name)
        for n in nodes:
            text = src[n.start_byte : n.end_byte].decode(errors="replace")
            records.append(
                {
                    "file": rel,
                    "line": n.start_point[0] + 1,
                    "start_byte": n.start_byte,
                    "end_byte": n.end_byte,
                    "text": text,
                }
            )

    if args.json:
        json.dump(records, sys.stdout, indent=1)
        print()
    else:
        for r in records:
            print(f"{r['file']}:{r['line']}: {r['text'].splitlines()[0][:160]}")
        print(f"-- {len(records)} match(es)", file=sys.stderr)

    # the absence guard: a zero-structural result with textual hits is NOT
    # a citable absence — the query may be wrong, or the code macro-generated.
    if not records and args.kind == "call" and args.name:
        hits = textual_hits(args.repo, args.prefixes, args.name)
        if hits:
            print(
                f"!! 0 structural matches but {hits} textual hit(s) for "
                f"'{args.name}' — inspect before citing absence",
                file=sys.stderr,
            )


if __name__ == "__main__":
    main()