#!/usr/bin/env python3
# Locate an LLVM install that ships the LLDB headers, mirroring the search order
# the old premake5.lua used. Meson calls this at configure time and parses the
# KEY=value lines below; run it by hand to see what would be picked.
#
# Precedence: -Dllvm_prefix (argv[1]) -> $LLVM_PREFIX -> vendored ext/llvm ->
# `llvm-config --prefix` -> per-platform well-known locations. A candidate only
# counts if it actually contains include/lldb.
#
# Output (stdout), only when a usable prefix is found:
#   prefix=<dir>
#   incdir=<dir>/include
#   libdir=<dir>/lib
#   lib=<full path to liblldb>
#   dll=<path>        (zero or more, Windows runtime libraries only)
# Exit status is non-zero when nothing usable was found.

import glob
import os
import platform
import subprocess
import sys

REPO_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
VENDORED = os.path.join(REPO_ROOT, "ext", "llvm")


def norm(path):
    # forward slashes so the value can be baked into a C string literal without
    # a backslash being read as an escape (matters for HSDBG_LLVM_PREFIX)
    return os.path.abspath(path).replace("\\", "/")


def usable(candidate):
    if not candidate:
        return None
    candidate = candidate.strip()
    if not candidate:
        return None
    prefix = norm(candidate)
    if os.path.isdir(os.path.join(prefix, "include", "lldb")):
        return prefix
    return None


def command_output(*args):
    try:
        out = subprocess.run(
            args, capture_output=True, text=True, check=False
        )
    except OSError:
        return None
    if out.returncode != 0:
        return None
    return out.stdout.strip() or None


def newest_of(pattern):
    matches = sorted(glob.glob(pattern))
    for candidate in reversed(matches):
        prefix = usable(candidate)
        if prefix:
            return prefix
    return None


def find_prefix(override):
    prefix = usable(override) or usable(os.environ.get("LLVM_PREFIX"))
    if prefix:
        return prefix

    prefix = usable(VENDORED)
    if prefix:
        return prefix

    prefix = usable(command_output("llvm-config", "--prefix"))
    if prefix:
        return prefix

    host = platform.system()

    if host == "Windows":
        program_files = os.environ.get("ProgramFiles")
        if program_files:
            prefix = usable(os.path.join(program_files, "LLVM"))
            if prefix:
                return prefix
        return newest_of("C:/Program Files/LLVM*")

    if host == "Darwin":
        return usable(command_output("brew", "--prefix", "llvm"))

    if host == "Linux":
        return newest_of("/usr/lib/llvm-*") or newest_of("/usr/local/llvm*")

    return None


def lldb_library(libdir):
    host = platform.system()
    if host == "Windows":
        names = ["liblldb.lib"]
    elif host == "Darwin":
        names = ["liblldb.dylib"]
    else:
        names = ["liblldb.so"]

    for name in names:
        candidate = os.path.join(libdir, name)
        if os.path.isfile(candidate):
            return norm(candidate)

    versioned = sorted(glob.glob(os.path.join(libdir, "liblldb.so.*")))
    if versioned:
        return norm(versioned[-1])

    # nothing on disk yet (e.g. a cross setup); hand back the expected path so
    # the caller gets a clear link-time error rather than a silent misconfigure
    return norm(os.path.join(libdir, names[0]))


def windows_dlls(prefix):
    bindir = os.path.join(prefix, "bin")
    runtimes = glob.glob(os.path.join(bindir, "liblldb.dll"))
    runtimes += glob.glob(os.path.join(bindir, "python*.dll"))
    if not runtimes:
        runtimes = [os.path.join(bindir, "liblldb.dll")]
    return [norm(path) for path in runtimes]


def main():
    override = sys.argv[1] if len(sys.argv) > 1 else ""
    prefix = find_prefix(override)

    if not prefix:
        sys.stderr.write("no llvm with lldb headers found\n")
        return 1

    incdir = norm(os.path.join(prefix, "include"))
    libdir = norm(os.path.join(prefix, "lib"))

    print("prefix=" + prefix)
    print("incdir=" + incdir)
    print("libdir=" + libdir)
    print("lib=" + lldb_library(libdir))

    if platform.system() == "Windows":
        for dll in windows_dlls(prefix):
            print("dll=" + dll)

    return 0


if __name__ == "__main__":
    sys.exit(main())