#!/usr/bin/env python3

"""A test case update script.

This script is a utility to update LLVM 'llvm-mca' based test cases with new
FileCheck patterns.
"""

import argparse
from collections import defaultdict
import glob
import os
import sys
import warnings

from UpdateTestChecks import common


COMMENT_CHAR = "#"
ADVERT_PREFIX = "{} NOTE: Assertions have been autogenerated by ".format(COMMENT_CHAR)
ADVERT = "{}utils/{}".format(ADVERT_PREFIX, os.path.basename(__file__))


class Error(Exception):
    """Generic Error that can be raised without printing a traceback."""

    pass


def _warn(msg):
    """Log a user warning to stderr."""
    warnings.warn(msg, Warning, stacklevel=2)


def _configure_warnings(args):
    warnings.resetwarnings()
    if args.w:
        warnings.simplefilter("ignore")
    if args.Werror:
        warnings.simplefilter("error")


def _showwarning(message, category, filename, lineno, file=None, line=None):
    """Version of warnings.showwarning that won't attempt to print out the
    line at the location of the warning if the line text is not explicitly
    specified.
    """
    if file is None:
        file = sys.stderr
    if line is None:
        line = ""
    file.write(warnings.formatwarning(message, category, filename, lineno, line))


def _parse_args():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("-w", action="store_true", help="suppress warnings")
    parser.add_argument(
        "-Werror", action="store_true", help="promote warnings to errors"
    )
    parser.add_argument(
        "--llvm-mca-binary",
        metavar="<path>",
        default="llvm-mca",
        help="the binary to use to generate the test case " "(default: llvm-mca)",
    )
    parser.add_argument("tests", metavar="<test-path>", nargs="+")
    args = common.parse_commandline_args(parser)

    _configure_warnings(args)

    if not args.llvm_mca_binary:
        raise Error("--llvm-mca-binary value cannot be empty string")

    if "llvm-mca" not in os.path.basename(args.llvm_mca_binary):
        _warn("unexpected binary name: {}".format(args.llvm_mca_binary))

    return args


def _get_run_infos(run_lines, args):
    run_infos = []
    for run_line in run_lines:
        try:
            (tool_cmd, filecheck_cmd) = tuple(
                [cmd.strip() for cmd in run_line.split("|", 1)]
            )
        except ValueError:
            _warn("could not split tool and filecheck commands: {}".format(run_line))
            continue

        common.verify_filecheck_prefixes(filecheck_cmd)
        tool_basename = os.path.splitext(os.path.basename(args.llvm_mca_binary))[0]

        if not tool_cmd.startswith(tool_basename + " "):
            _warn("skipping non-{} RUN line: {}".format(tool_basename, run_line))
            continue

        if not filecheck_cmd.startswith("FileCheck "):
            _warn("skipping non-FileCheck RUN line: {}".format(run_line))
            continue

        tool_cmd_args = tool_cmd[len(tool_basename) :].strip()
        tool_cmd_args = tool_cmd_args.replace("< %s", "").replace("%s", "").strip()

        check_prefixes = common.get_check_prefixes(filecheck_cmd)

        run_infos.append((check_prefixes, tool_cmd_args))

    return run_infos


def _break_down_block(block_info, common_prefix):
    """Given a block_info, see if we can analyze it further to let us break it
    down by prefix per-line rather than per-block.
    """
    texts = block_info.keys()
    prefixes = list(block_info.values())
    # Split the lines from each of the incoming block_texts and zip them so that
    # each element contains the corresponding lines from each text.  E.g.
    #
    # block_text_1: A   # line 1
    #               B   # line 2
    #
    # block_text_2: A   # line 1
    #               C   # line 2
    #
    # would become:
    #
    # [(A, A),   # line 1
    #  (B, C)]   # line 2
    #
    line_tuples = list(zip(*list((text.splitlines() for text in texts))))

    # To simplify output, we'll only proceed if the very first line of the block
    # texts is common to each of them.
    if len(set(line_tuples[0])) != 1:
        return []

    result = []
    lresult = defaultdict(list)
    for i, line in enumerate(line_tuples):
        if len(set(line)) == 1:
            # We're about to output a line with the common prefix.  This is a sync
            # point so flush any batched-up lines one prefix at a time to the output
            # first.
            for prefix in sorted(lresult):
                result.extend(lresult[prefix])
            lresult = defaultdict(list)

            # The line is common to each block so output with the common prefix.
            result.append((common_prefix, line[0]))
        else:
            # The line is not common to each block, or we don't have a common prefix.
            # If there are no prefixes available, warn and bail out.
            if not prefixes[0]:
                _warn(
                    "multiple lines not disambiguated by prefixes:\n{}\n"
                    "Some blocks may be skipped entirely as a result.".format(
                        "\n".join("  - {}".format(l) for l in line)
                    )
                )
                return []

            # Iterate through the line from each of the blocks and add the line with
            # the corresponding prefix to the current batch of results so that we can
            # later output them per-prefix.
            for i, l in enumerate(line):
                for prefix in prefixes[i]:
                    lresult[prefix].append((prefix, l))

    # Flush any remaining batched-up lines one prefix at a time to the output.
    for prefix in sorted(lresult):
        result.extend(lresult[prefix])
    return result


def _get_useful_prefix_info(run_infos):
    """Given the run_infos, calculate any prefixes that are common to every one,
    and the length of the longest prefix string.
    """
    try:
        all_sets = [set(s) for s in list(zip(*run_infos))[0]]
        common_to_all = set.intersection(*all_sets)
        longest_prefix_len = max(len(p) for p in set.union(*all_sets))
    except IndexError:
        common_to_all = []
        longest_prefix_len = 0
    else:
        if len(common_to_all) > 1:
            _warn("Multiple prefixes common to all RUN lines: {}".format(common_to_all))
        if common_to_all:
            common_to_all = sorted(common_to_all)[0]
    return common_to_all, longest_prefix_len


def _align_matching_blocks(all_blocks, farthest_indexes):
    """Some sub-sequences of blocks may be common to multiple lists of blocks,
    but at different indexes in each one.

    For example, in the following case, A,B,E,F, and H are common to both
    sets, but only A and B would be identified as such due to the indexes
    matching:

    index | 0 1 2 3 4 5 6
    ------+--------------
    setA  | A B C D E F H
    setB  | A B E F G H

    This function attempts to align the indexes of matching blocks by
    inserting empty blocks into the block list. With this approach, A, B, E,
    F, and H would now be able to be identified as matching blocks:

    index | 0 1 2 3 4 5 6 7
    ------+----------------
    setA  | A B C D E F   H
    setB  | A B     E F G H
    """

    # "Farthest block analysis": essentially, iterate over all blocks and find
    # the highest index into a block list for the first instance of each block.
    # This is relatively expensive, but we're dealing with small numbers of
    # blocks so it doesn't make a perceivable difference to user time.
    for blocks in all_blocks.values():
        for block in blocks:
            if not block:
                continue

            index = blocks.index(block)

            if index > farthest_indexes[block]:
                farthest_indexes[block] = index

    # Use the results of the above analysis to identify any blocks that can be
    # shunted along to match the farthest index value.
    for blocks in all_blocks.values():
        for index, block in enumerate(blocks):
            if not block:
                continue

            changed = False
            # If the block has not already been subject to alignment (i.e. if the
            # previous block is not empty) then insert empty blocks until the index
            # matches the farthest index identified for that block.
            if (index > 0) and blocks[index - 1]:
                while index < farthest_indexes[block]:
                    blocks.insert(index, "")
                    index += 1
                    changed = True

            if changed:
                # Bail out.  We'll need to re-do the farthest block analysis now that
                # we've inserted some blocks.
                return True

    return False


def _get_block_infos(run_infos, test_path, args, common_prefix):  # noqa
    """For each run line, run the tool with the specified args and collect the
    output. We use the concept of 'blocks' for uniquing, where a block is
    a series of lines of text with no more than one newline character between
    each one.  For example:

    This
    is
    one
    block

    This is
    another block

    This is yet another block

    We then build up a 'block_infos' structure containing a dict where the
    text of each block is the key and a list of the sets of prefixes that may
    generate that particular block.  This then goes through a series of
    transformations to minimise the amount of CHECK lines that need to be
    written by taking advantage of common prefixes.
    """

    def _block_key(tool_args, prefixes):
        """Get a hashable key based on the current tool_args and prefixes."""
        return " ".join([tool_args] + prefixes)

    all_blocks = {}
    max_block_len = 0

    # A cache of the furthest-back position in any block list of the first
    # instance of each block, indexed by the block itself.
    farthest_indexes = defaultdict(int)

    # Run the tool for each run line to generate all of the blocks.
    for prefixes, tool_args in run_infos:
        key = _block_key(tool_args, prefixes)
        raw_tool_output = common.invoke_tool(args.llvm_mca_binary, tool_args, test_path)

        # Replace any lines consisting of purely whitespace with empty lines.
        raw_tool_output = "\n".join(
            line if line.strip() else "" for line in raw_tool_output.splitlines()
        )

        # Split blocks, stripping all trailing whitespace, but keeping preceding
        # whitespace except for newlines so that columns will line up visually.
        all_blocks[key] = [
            b.lstrip("\n").rstrip() for b in raw_tool_output.split("\n\n")
        ]
        max_block_len = max(max_block_len, len(all_blocks[key]))

        # Attempt to align matching blocks until no more changes can be made.
        made_changes = True
        while made_changes:
            made_changes = _align_matching_blocks(all_blocks, farthest_indexes)

    # If necessary, pad the lists of blocks with empty blocks so that they are
    # all the same length.
    for key in all_blocks:
        len_to_pad = max_block_len - len(all_blocks[key])
        all_blocks[key] += [""] * len_to_pad

    # Create the block_infos structure where it is a nested dict in the form of:
    # block number -> block text -> list of prefix sets
    block_infos = defaultdict(lambda: defaultdict(list))
    for prefixes, tool_args in run_infos:
        key = _block_key(tool_args, prefixes)
        for block_num, block_text in enumerate(all_blocks[key]):
            block_infos[block_num][block_text].append(set(prefixes))

    # Now go through the block_infos structure and attempt to smartly prune the
    # number of prefixes per block to the minimal set possible to output.
    for block_num in range(len(block_infos)):
        # When there are multiple block texts for a block num, remove any
        # prefixes that are common to more than one of them.
        # E.g. [ [{ALL,FOO}] , [{ALL,BAR}] ] -> [ [{FOO}] , [{BAR}] ]
        all_sets = [s for s in block_infos[block_num].values()]
        pruned_sets = []

        for i, setlist in enumerate(all_sets):
            other_set_values = set(
                [
                    elem
                    for j, setlist2 in enumerate(all_sets)
                    for set_ in setlist2
                    for elem in set_
                    if i != j
                ]
            )
            pruned_sets.append([s - other_set_values for s in setlist])

        for i, block_text in enumerate(block_infos[block_num]):

            # When a block text matches multiple sets of prefixes, try removing any
            # prefixes that aren't common to all of them.
            # E.g. [ {ALL,FOO} , {ALL,BAR} ] -> [{ALL}]
            common_values = set.intersection(*pruned_sets[i])
            if common_values:
                pruned_sets[i] = [common_values]

            # Everything should be uniqued as much as possible by now.  Apply the
            # newly pruned sets to the block_infos structure.
            # If there are any blocks of text that still match multiple prefixes,
            # output a warning.
            current_set = set()
            for s in pruned_sets[i]:
                s = sorted(list(s))
                if s:
                    current_set.add(s[0])
                    if len(s) > 1:
                        _warn(
                            "Multiple prefixes generating same output: {} "
                            "(discarding {})".format(",".join(s), ",".join(s[1:]))
                        )

            if block_text and not current_set:
                raise Error(
                    "block not captured by existing prefixes:\n\n{}".format(block_text)
                )
            block_infos[block_num][block_text] = sorted(list(current_set))

        # If we have multiple block_texts, try to break them down further to avoid
        # the case where we have very similar block_texts repeated after each
        # other.
        if common_prefix and len(block_infos[block_num]) > 1:
            # We'll only attempt this if each of the block_texts have the same number
            # of lines as each other.
            same_num_Lines = (
                len(set(len(k.splitlines()) for k in block_infos[block_num].keys()))
                == 1
            )
            if same_num_Lines:
                breakdown = _break_down_block(block_infos[block_num], common_prefix)
                if breakdown:
                    block_infos[block_num] = breakdown

    return block_infos


def _write_block(output, block, not_prefix_set, common_prefix, prefix_pad):
    """Write an individual block, with correct padding on the prefixes.
    Returns a set of all of the prefixes that it has written.
    """
    end_prefix = ":     "
    previous_prefix = None
    num_lines_of_prefix = 0
    written_prefixes = set()

    for prefix, line in block:
        if prefix in not_prefix_set:
            _warn(
                'not writing for prefix {0} due to presence of "{0}-NOT:" '
                "in input file.".format(prefix)
            )
            continue

        # If the previous line isn't already blank and we're writing more than one
        # line for the current prefix output a blank line first, unless either the
        # current of previous prefix is common to all.
        num_lines_of_prefix += 1
        if prefix != previous_prefix:
            if output and output[-1]:
                if num_lines_of_prefix > 1 or any(
                    p == common_prefix for p in (prefix, previous_prefix)
                ):
                    output.append("")
            num_lines_of_prefix = 0
            previous_prefix = prefix

        written_prefixes.add(prefix)
        output.append(
            "{} {}{}{} {}".format(
                COMMENT_CHAR, prefix, end_prefix, " " * (prefix_pad - len(prefix)), line
            ).rstrip()
        )
        end_prefix = "-NEXT:"

    output.append("")
    return written_prefixes


def _write_output(
    test_path,
    input_lines,
    prefix_list,
    block_infos,  # noqa
    args,
    common_prefix,
    prefix_pad,
):
    prefix_set = set([prefix for prefixes, _ in prefix_list for prefix in prefixes])
    not_prefix_set = set()

    output_lines = []
    for input_line in input_lines:
        if input_line.startswith(ADVERT_PREFIX):
            continue

        if input_line.startswith(COMMENT_CHAR):
            m = common.CHECK_RE.match(input_line)
            try:
                prefix = m.group(1)
            except AttributeError:
                prefix = None

            if "{}-NOT:".format(prefix) in input_line:
                not_prefix_set.add(prefix)

            if prefix not in prefix_set or prefix in not_prefix_set:
                output_lines.append(input_line)
                continue

        if common.should_add_line_to_output(input_line, prefix_set):
            # This input line of the function body will go as-is into the output.
            # Except make leading whitespace uniform: 2 spaces.
            input_line = common.SCRUB_LEADING_WHITESPACE_RE.sub(r"  ", input_line)

            # Skip empty lines if the previous output line is also empty.
            if input_line or output_lines[-1]:
                output_lines.append(input_line)
        else:
            continue

    # Add a blank line before the new checks if required.
    if len(output_lines) > 0 and output_lines[-1]:
        output_lines.append("")

    output_check_lines = []
    used_prefixes = set()
    for block_num in range(len(block_infos)):
        if type(block_infos[block_num]) is list:
            # The block is of the type output from _break_down_block().
            used_prefixes |= _write_block(
                output_check_lines,
                block_infos[block_num],
                not_prefix_set,
                common_prefix,
                prefix_pad,
            )
        else:
            # _break_down_block() was unable to do do anything so output the block
            # as-is.

            # Rather than writing out each block as soon we encounter it, save it
            # indexed by prefix so that we can write all of the blocks out sorted by
            # prefix at the end.
            output_blocks = defaultdict(list)

            for block_text in sorted(block_infos[block_num]):

                if not block_text:
                    continue

                lines = block_text.split("\n")
                for prefix in block_infos[block_num][block_text]:
                    assert prefix not in output_blocks
                    used_prefixes |= _write_block(
                        output_blocks[prefix],
                        [(prefix, line) for line in lines],
                        not_prefix_set,
                        common_prefix,
                        prefix_pad,
                    )

            for prefix in sorted(output_blocks):
                output_check_lines.extend(output_blocks[prefix])

    unused_prefixes = (prefix_set - not_prefix_set) - used_prefixes
    if unused_prefixes:
        raise Error("unused prefixes: {}".format(sorted(unused_prefixes)))

    if output_check_lines:
        output_lines.insert(0, ADVERT)
        output_lines.extend(output_check_lines)

    # The file should not end with two newlines. It creates unnecessary churn.
    while len(output_lines) > 0 and output_lines[-1] == "":
        output_lines.pop()

    if input_lines == output_lines:
        sys.stderr.write("            [unchanged]\n")
        return
    sys.stderr.write("      [{} lines total]\n".format(len(output_lines)))

    common.debug("Writing", len(output_lines), "lines to", test_path, "..\n\n")

    with open(test_path, "wb") as f:
        f.writelines(["{}\n".format(l).encode("utf-8") for l in output_lines])


def main():
    args = _parse_args()
    test_paths = [test for pattern in args.tests for test in glob.glob(pattern)]
    for test_path in test_paths:
        sys.stderr.write("Test: {}\n".format(test_path))

        # Call this per test. By default each warning will only be written once
        # per source location. Reset the warning filter so that now each warning
        # will be written once per source location per test.
        _configure_warnings(args)

        if not os.path.isfile(test_path):
            raise Error("could not find test file: {}".format(test_path))

        with open(test_path) as f:
            input_lines = [l.rstrip() for l in f]

        run_lines = common.find_run_lines(test_path, input_lines)
        run_infos = _get_run_infos(run_lines, args)
        common_prefix, prefix_pad = _get_useful_prefix_info(run_infos)
        block_infos = _get_block_infos(run_infos, test_path, args, common_prefix)
        _write_output(
            test_path,
            input_lines,
            run_infos,
            block_infos,
            args,
            common_prefix,
            prefix_pad,
        )

    return 0


if __name__ == "__main__":
    try:
        warnings.showwarning = _showwarning
        sys.exit(main())
    except Error as e:
        sys.stdout.write("error: {}\n".format(e))
        sys.exit(1)