#!/usr/bin/env python3

import argparse
import fnmatch
import sys
import os
import re
import shutil
from pathlib import Path
from difflib import unified_diff

# ---------- actual list of lints to apply (or disapply) ----------

# NOTE: We should NEVER have a `deny` for a built-in rustc lint.
# It's okay to deny clippy lints, but if we deny rustc lints,
# a future version of the compiler might refuse to build our code
# entirely.

WANT_LINTS = """
#![allow(renamed_and_removed_lints)] // @@REMOVE_WHEN(ci_arti_stable)
#![allow(unknown_lints)] // @@REMOVE_WHEN(ci_arti_nightly)
#![warn(missing_docs)]
#![warn(noop_method_call)]
#![warn(unreachable_pub)]
#![warn(clippy::all)]
#![deny(clippy::await_holding_lock)]
#![deny(clippy::cargo_common_metadata)]
#![deny(clippy::cast_lossless)]
#![deny(clippy::checked_conversions)]
#![allow(clippy::cognitive_complexity)] // See arti#2556
#![deny(clippy::debug_assert_with_mut_call)]
#![deny(clippy::exhaustive_enums)]
#![deny(clippy::exhaustive_structs)]
#![deny(clippy::expl_impl_clone_on_copy)]
#![deny(clippy::fallible_impl_from)]
#![deny(clippy::implicit_clone)]
#![deny(clippy::large_stack_arrays)]
#![warn(clippy::manual_ok_or)]
#![deny(clippy::missing_docs_in_private_items)]
#![warn(clippy::needless_borrow)]
#![warn(clippy::needless_pass_by_value)]
#![warn(clippy::option_option)]
#![deny(clippy::print_stderr)]
#![deny(clippy::print_stdout)]
#![warn(clippy::rc_buffer)]
#![deny(clippy::ref_option_ref)]
#![warn(clippy::semicolon_if_nothing_returned)]
#![warn(clippy::trait_duplication_in_bounds)]
#![deny(clippy::unchecked_time_subtraction)]
#![deny(clippy::unnecessary_wraps)]
#![warn(clippy::unseparated_literal_suffix)]
#![deny(clippy::unwrap_used)]
#![deny(clippy::mod_module_files)]
#![allow(clippy::let_unit_value)] // This can reasonably be done for explicitness
#![allow(clippy::uninlined_format_args)]
#![allow(clippy::significant_drop_in_scrutinee)] // arti/-/merge_requests/588/#note_2812945
#![allow(clippy::result_large_err)] // temporary workaround for arti#587
#![allow(clippy::needless_raw_string_hashes)] // complained-about code is fine, often best
#![allow(clippy::needless_lifetimes)] // See arti#1765
#![allow(mismatched_lifetime_syntaxes)] // temporary workaround for arti#2060
#![allow(clippy::collapsible_if)] // See arti#2342
#![deny(clippy::unused_async)]
#![deny(clippy::string_slice)] // See arti#2571
"""

# ---------- list of lints to apply or disapply *in tests* ----------

TEST_LINTS = """
#![allow(clippy::bool_assert_comparison)]
#![allow(clippy::clone_on_copy)]
#![allow(clippy::dbg_macro)]
#![allow(clippy::mixed_attributes_style)]
#![allow(clippy::print_stderr)]
#![allow(clippy::print_stdout)]
#![allow(clippy::single_char_pattern)]
#![allow(clippy::unwrap_used)]
#![allow(clippy::unchecked_time_subtraction)]
#![allow(clippy::useless_vec)]
#![allow(clippy::needless_pass_by_value)]
#![allow(clippy::string_slice)] // See arti#2571
"""

# ---------- list of lints to apply or disapply *in examples* ----------

EXAMPLE_LINTS = """
#![allow(unknown_lints)] // @@REMOVE_WHEN(ci_arti_nightly)
""" + TEST_LINTS.strip()


# ---------- some notes about lints we might use - NOT USED by any code here ----------

SOON = """
"""

WISH_WE_COULD = """
#![warn(unused_crate_dependencies)]
"""

DECIDED_NOT = """
#![deny(clippy::redundant_pub_crate)]
#![deny(clippy::future_not_send)]
#![deny(clippy::redundant_closure_for_method_calls)]
#![deny(clippy::panic)]
#![deny(clippy::if_then_some_else_none)]
#![deny(clippy::expect_used)]
#![deny(clippy::option_if_let_else)]
#![deny(missing_debug_implementations)]
#![deny(clippy::pub_enum_variant_names)]
"""

# ---------- code for autoprocessing Rust source files ----------

PAT = re.compile(r"^ *#!\[(?:cfg_attr\(.*)?(allow|deny|warn)")

LINT_LISTS = {
    "lint": WANT_LINTS,
    "test lint": TEST_LINTS,
    "example lint": EXAMPLE_LINTS,
}
# The start delimiter is a regular comment.
START_LINE = re.compile(r"^(\s*)// @@ begin (.*) list")

# End delimiter is Rustdoc containing an HTML comment, because rustfmt
# *really really* hates comments that come after things.
# Finishing the automaintained block with just a blank line is too much of a hazard.
# It does end up in the output HTML from Rustdoc, but it is harmless there.
END_LINE = re.compile(r"^\s*//! <!-- @@ end (.*) list")

opts = None
deferred_errors = []


class ImproperFile(Exception):
    def __init__(self, lno, message):
        self.lno = lno
        self.message = message


def strip_lints_containing(s):
    """Remove every lint containing 's'."""

    def rmv_lints(inp, s):
        return "\n".join(line for line in inp.split("\n") if s not in line)

    global LINT_LISTS
    LINT_LISTS = dict((k, rmv_lints(v, s)) for (k, v) in LINT_LISTS.items())


def filter_file(lints, inp, outp, insist):
    in_lint_list = None
    found_lint_list = False
    lno = 0
    for line in inp.readlines():
        lno += 1

        if start_match := START_LINE.match(line):
            if in_lint_list:
                raise ImproperFile(
                    lno, 'found "@@ begin lint list" but inside lint list'
                )
            found_lint_list = True
            indent = start_match.group(1)
            in_lint_list = start_match.group(2)
        elif end_match := END_LINE.match(line):
            if not in_lint_list:
                raise ImproperFile(
                    lno, 'found "@@ end lint list" but not inside lint list'
                )
            if in_lint_list != end_match.group(1):
                raise ImproperFile(
                    lno,
                    "found end tag "
                    + end_match.group(1)
                    + " but expected "
                    + in_lint_list,
                )

            try:
                lints = LINT_LISTS[in_lint_list]
            except KeyError:
                raise ImproperFile(lno, "No such lint list as " + in_lint_list)
            for lint in lints.strip().split("\n"):
                outp.write(indent + lint + "\n")
            in_lint_list = None
        elif in_lint_list:
            if not PAT.match(line):
                raise ImproperFile(lno, "entry in lint list does not look like a lint")
            # do not send to output
            continue
        outp.write(line)
    if in_lint_list:
        raise ImproperFile(
            lno, 'missing "@@ lint list" delimiter, still in lint list at EOF'
        )
    if insist and not found_lint_list:
        raise ImproperFile(
            lno, "standard lint list block seems to be missing (wrong delimiters?)"
        )


def process(lints, fn, always_insist):
    insist = (
        always_insist
        or fnmatch.fnmatch(fn, "crates/*/src/lib.rs")
        or fnmatch.fnmatch(fn, "crates/*/src/main.rs")
    )

    tmp_name = fn + ".tmp~"
    # Explicitly specify UTF-8 encoding
    # because Windows defaults to a system locale encoding (e.g., GBK or cp1252)
    outp = open(tmp_name, "w", encoding="utf-8")
    inp = open(fn, "r", encoding="utf-8")
    try:
        filter_file(lints, inp, outp, insist)
    except ImproperFile as e:
        print("%s:%d: %s" % (fn, e.lno, e.message), file=sys.stderr)
        deferred_errors.append(fn)
        os.remove(tmp_name)  # this tmp file is probably partial
        return

    inp.close()
    outp.close()

    if opts.check:
        mh = check_diff(fn, tmp_name)
        if mh:
            sys.stdout.write(mh)
            deferred_errors.append(fn)
    else:
        shutil.move(tmp_name, fn)


def check_diff(fn: str, tmp_name: str) -> str | None:
    """
    fn = original file name
    tmp_name = temporary file name which contains the modified content
    When caller call the function,
    caller itself will check if the return value is None or not.
    If it is not None,
    caller should print the diff to stdout
    and add the file name to deferred_errors list.
    Like:
    ```python
    sys.stdout.writelines(diff)
    deferred_errors.append(fn)
    """
    with open(fn, "r", encoding="utf-8") as original, open(
        tmp_name, "r", encoding="utf-8"
    ) as modified:
        original_lines = original.readlines()
        modified_lines = modified.readlines()

    if original_lines != modified_lines:
        diff = unified_diff(
            original_lines,
            modified_lines,
            fromfile=fn,
            tofile=tmp_name,
        )
        return "".join(diff)
    return None


def main(lints, files):
    if not os.path.exists("./crates/tor-proto/src/lib.rs"):
        print("Run this from the top level of an arti repo.")
        sys.exit(1)

    always_insist = True
    if not files:
        files = [str(file) for file in Path("./").rglob("*.rs")]
        always_insist = False

    if opts.ci_nightly:
        strip_lints_containing("@@REMOVE_WHEN(ci_arti_nightly)")
    if opts.ci_stable:
        strip_lints_containing("@@REMOVE_WHEN(ci_arti_stable)")

    for fn in files:
        process(lints, fn, always_insist)

    if len(deferred_errors) > 0:
        print(
            "\n"
            + sys.argv[0]
            + ": standard lint block mismatch in the following files:\n  "
            + ", ".join(deferred_errors),
            file=sys.stderr,
        )
        print("Run " + sys.argv[0] + " (possibly after editing it) to fix.")
        sys.exit(1)


if __name__ == "__main__":
    parser = argparse.ArgumentParser("standardise Rust lint blocks")
    parser.add_argument("--check", action="store_true")
    parser.add_argument("--ci-nightly", action="store_true")
    parser.add_argument("--ci-stable", action="store_true")
    parser.add_argument("file", nargs="*")
    opts = parser.parse_args()

    main(WANT_LINTS, opts.file)