#!/usr/bin/env python3
"""Walk every .js in a package and check that each require()/import target resolves,
following Node's resolution rules against the vendored node_modules tree."""
import json
import os
import re
import sys

ROOT = os.path.abspath(sys.argv[1])
BUILTIN = set("""assert async_hooks buffer child_process cluster console constants crypto dgram
diagnostics_channel dns domain events fs http http2 https inspector module net os path
perf_hooks process punycode querystring readline repl stream string_decoder sys timers tls
trace_events tty url util v8 vm wasi worker_threads zlib""".split())

SPEC = re.compile(r"""(?:require\(|(?:^|[\s;{}])(?:import|export)[^;\n]*?\bfrom\s*|import\()\s*['"]([^'"]+)['"]""", re.M)
DYNAMIC = re.compile(r"require\(\s*[^'\")\s]")
COMMENTS = re.compile(r"/\*.*?\*/|^\s*//.*$", re.S | re.M)
# Optional at runtime: loaded only under a config or platform this module never uses.
OPTIONAL = {"re2", "expo-random", "tinybench", "uri-js", "neostandard"}
SKIP_DIRS = ("test", "benchmark", "benchmarks", "example", "examples", ".github")


def load_json(p):
    try:
        with open(p) as fh:
            return json.load(fh)
    except Exception:
        return {}


def resolve_file(base):
    for cand in (base, base + ".js", base + ".json", base + ".cjs", base + ".mjs", base + ".node"):
        if os.path.isfile(cand):
            return cand
    if os.path.isdir(base):
        pj = load_json(os.path.join(base, "package.json"))
        for key in ("main", "module"):
            if isinstance(pj.get(key), str):
                hit = resolve_file(os.path.join(base, pj[key]))
                if hit:
                    return hit
        if pj.get("exports"):
            return base  # exports map: trust it, too complex to model here
        for idx in ("index.js", "index.json", "index.cjs", "index.node"):
            if os.path.isfile(os.path.join(base, idx)):
                return os.path.join(base, idx)
    return None


def resolve_bare(spec, from_dir):
    d = from_dir
    while True:
        hit = resolve_file(os.path.join(d, "node_modules", *spec.split("/")))
        if hit:
            return hit
        # scoped or deep import into a package that exists
        parts = spec.split("/")
        pkg = "/".join(parts[:2]) if spec.startswith("@") else parts[0]
        pkg_dir = os.path.join(d, "node_modules", *pkg.split("/"))
        if os.path.isdir(pkg_dir) and len(parts) > (2 if spec.startswith("@") else 1):
            sub = resolve_file(os.path.join(pkg_dir, *parts[(2 if spec.startswith("@") else 1):]))
            if sub:
                return sub
            if load_json(os.path.join(pkg_dir, "package.json")).get("exports"):
                return pkg_dir
        if os.path.dirname(d) == d or len(d) <= len(ROOT) - 1:
            return None
        d = os.path.dirname(d)


missing, dynamic, files, optional_hits = [], [], 0, set()
for dirpath, dirnames, filenames in os.walk(ROOT):
    dirnames[:] = [d for d in dirnames if d not in SKIP_DIRS]
    if dirpath.endswith((os.sep + "browser", os.sep + "types")):
        continue
    for fn in filenames:
        if not fn.endswith((".js", ".cjs", ".mjs")):
            continue
        if fn.endswith((".native.js", ".browser.js")) or fn.startswith("eslint.config"):
            continue
        path = os.path.join(dirpath, fn)
        files += 1
        try:
            src = COMMENTS.sub("", open(path, encoding="utf-8", errors="replace").read())
        except OSError:
            continue
        if DYNAMIC.search(src):
            dynamic.append(os.path.relpath(path, ROOT))
        for spec in set(SPEC.findall(src)):
            if spec.startswith("node:") or spec.split("/")[0] in BUILTIN:
                continue
            if spec in OPTIONAL:
                optional_hits.add((os.path.relpath(path, ROOT), spec))
                continue
            if spec.startswith("."):
                hit = resolve_file(os.path.normpath(os.path.join(dirpath, spec)))
            else:
                hit = resolve_bare(spec, dirpath)
            if not hit:
                missing.append((os.path.relpath(path, ROOT), spec))

print("scanned %d js files" % files)
if dynamic:
    print("\n%d file(s) use a computed require() (not statically checkable):" % len(dynamic))
    for d in sorted(dynamic)[:12]:
        print("   ", d)
if optional_hits:
    print("\n%d optional dep(s), not loaded on this platform/config:" % len(optional_hits))
    for f, spec in sorted(optional_hits):
        print("    %-64s -> %s" % (f, spec))
if missing:
    print("\nUNRESOLVED (%d):" % len(missing))
    for f, s in sorted(set(missing)):
        print("   %-70s -> %s" % (f, s))
    sys.exit(1)
print("\nevery static require/import resolves")