#!/usr/bin/env python3

# This script finds and prints the various versions in this project: wasi-sdk
# itself, LLVM, and the Git revisions of dependencies.
#
# Usage: version [wasi-sdk|llvm|llvm-major|dump] [--llvm-dir=<non-project dir>]

import argparse
import os
import subprocess
import sys

# The number of characters to use for the abbreviated Git revision.
GIT_REF_LEN = 12


def exec(command, cwd):
    result = subprocess.run(command, stdout=subprocess.PIPE,
                            universal_newlines=True, check=True, cwd=cwd)
    return result.stdout.strip()


def git_commit(dir):
    return exec(['git', 'rev-parse', f'--short={GIT_REF_LEN}', 'HEAD'], dir)


def parse_git_version(version):
    # Parse, e.g.: wasi-sdk-$version-0-g317548590b40+m
    parts = version.replace('+', '-').split('-')
    assert parts.pop(0) == 'wasi'
    assert parts.pop(0) == 'sdk'

    dirty = False
    git = parts.pop()
    assert git is not None
    # If git printed `+m` at the end then we're dirty and the next-to-last part
    # is now the git commit
    if git == 'm':
        dirty = True
        git = parts.pop()

    # If the git commit doesn't start with `g` then that's not actually a git
    # commit. Technically this should look for `GIT_REF_LEN` hexadecimal digits,
    # but that's left for later.
    if not git.startswith('g'):
        parts.append(git)
        git = None

    # The next part in the back is the number of commits since the tag, and the
    # first part in the front is the major version of wasi-sdk itself.
    commits_since_tag = parts.pop()
    major_version = parts.pop(0)

    # If there are 0 commits since the last tag then forcibly drop the git part
    # as that produces a nice clean version for tagged commits.
    if commits_since_tag == '0':
        git = None

    # Pretend the commits since the tag is a minor version number, and then
    # add in any other words after the tag to the prerelease part, if any.
    ret = f'{major_version}.{commits_since_tag}'
    if len(parts) > 0:
        ret += '-' + '-'.join(parts)

    # Throw on git/dirty info
    if git:
        ret += git
    if dirty:
        ret += '+m'
    return ret


# Some inline tests to check Git version parsing:
assert parse_git_version('wasi-sdk-21-1-g317548590b40+m') == '21.1g317548590b40+m'
assert parse_git_version('wasi-sdk-21-2+m') == '21.2+m'
assert parse_git_version('wasi-sdk-23-0-g317548590b40') == '23.0'
assert parse_git_version('wasi-sdk-23-tag-0-g317548590b40') == '23.0-tag'
assert parse_git_version('wasi-sdk-23-some-tag-0-g317548590b40') == '23.0-some-tag'
assert parse_git_version('wasi-sdk-23-some.tag-0-g317548590b40') == '23.0-some.tag'
assert parse_git_version('wasi-sdk-23-tag.rc1-1-g100') == '23.1-tag.rc1g100'

def git_version():
    version = exec(['git', 'describe', '--long', '--candidates=999',
                    '--match=wasi-sdk-*', '--dirty=+m', f'--abbrev={GIT_REF_LEN}'],
                    os.path.dirname(sys.argv[0]))
    return parse_git_version(version)


def parse_cmake_set(line):
    return line.split(' ')[1].split(')')[0]


def llvm_cmake_version(llvm_dir):
    path = f'{llvm_dir}/cmake/Modules/LLVMVersion.cmake'
    if not os.path.exists(path):
        # Handle older LLVM versions; see #399.
        path = f'{llvm_dir}/llvm/CMakeLists.txt'
    with open(path) as file:
        for line in file:
            line = line.strip()
            if line.startswith('set(LLVM_VERSION_MAJOR'):
                llvm_version_major = parse_cmake_set(line)
            elif line.startswith('set(LLVM_VERSION_MINOR'):
                llvm_version_minor = parse_cmake_set(line)
            elif line.startswith('set(LLVM_VERSION_PATCH'):
                llvm_version_patch = parse_cmake_set(line)
    return llvm_version_major, llvm_version_minor, llvm_version_patch


def main(action, llvm_dir):
    if action == 'wasi-sdk':
        print(git_version())
    elif action == 'llvm':
        major, minor, path = llvm_cmake_version(llvm_dir)
        print(f'{major}.{minor}.{path}')
    elif action == 'llvm-major':
        major, _, _ = llvm_cmake_version(llvm_dir)
        print(major)
    elif action == 'dump':
        print(git_version())
        print(f'wasi-libc: {git_commit("src/wasi-libc")}')
        print(f'llvm: {git_commit(llvm_dir)}')
        major, minor, path = llvm_cmake_version(llvm_dir)
        print(f'llvm-version: {major}.{minor}.{path}')
        print(f'config: {git_commit("src/config")}')


if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description='Print the various kinds of versions in wasi-sdk')
    parser.add_argument('action',
                        choices=['wasi-sdk', 'llvm', 'llvm-major', 'dump'],
                        nargs='?',
                        default='wasi-sdk',
                        help='Which kind of version to print (default: wasi-sdk).')
    parser.add_argument('--llvm-dir',
                        nargs='?',
                        default='src/llvm-project',
                        help='Override the location of the LLVM source directory (default: src/llvm-project).')
    args = parser.parse_args()
    main(args.action, args.llvm_dir)
    sys.exit(0)