import os
import re
import sys
import subprocess
from os import walk


def run_command(command, cwd=None):
    p = subprocess.Popen(command, cwd=cwd)
    if p.wait() != 0:
        print("command `{}` failed...".format(" ".join(command)))
        sys.exit(1)


def clone_repository(repo_name, path, repo_url, sub_path=None):
    if os.path.exists(path):
        while True:
            choice = input("There is already a `{}` folder, do you want to update it? [y/N]".format(repo_name))
            if choice == "" or choice.lower() == "n":
                print("Skipping repository update.")
                return
            elif choice.lower() == "y":
                print("Updating repository...")
                run_command(["git", "pull", "origin"], cwd=path)
                return
            else:
                print("Didn't understand answer...")
    print("Cloning {} repository...".format(repo_name))
    if sub_path is None:
        run_command(["git", "clone", repo_url, "--depth", "1", path])
    else:
        run_command(["git", "clone", repo_url, "--filter=tree:0", "--no-checkout", path])
        run_command(["git", "sparse-checkout", "init"], cwd=path)
        run_command(["git", "sparse-checkout", "set", "add", sub_path], cwd=path)
        run_command(["git", "checkout"], cwd=path)


def extract_instrinsics(intrinsics, file):
    print("Extracting intrinsics from `{}`...".format(file))
    with open(file, "r", encoding="utf8") as f:
        content = f.read()

    lines = content.splitlines()
    pos = 0
    current_arch = None
    while pos < len(lines):
        line = lines[pos].strip()
        if line.startswith("let TargetPrefix ="):
            current_arch = line.split('"')[1].strip()
            if len(current_arch) == 0:
                current_arch = None
        elif current_arch is None:
            pass
        elif line == "}":
            current_arch = None
        elif line.startswith("def "):
            content = ""
            while not content.endswith(";") and pos < len(lines):
                line = lines[pos].split(" // ")[0].strip()
                content += line
                pos += 1
            entries = re.findall('GCCBuiltin<"(\\w+)">', content)
            if len(entries) > 0:
                intrinsic = content.split(":")[0].split(" ")[1].strip()
                intrinsic = intrinsic.split("_")
                if len(intrinsic) < 2 or intrinsic[0] != "int":
                    continue
                intrinsic[0] = "llvm"
                intrinsic = ".".join(intrinsic)
                if current_arch not in intrinsics:
                    intrinsics[current_arch] = []
                for entry in entries:
                    intrinsics[current_arch].append('"{}" => "{}",'.format(intrinsic, entry))
            continue
        pos += 1
        continue
    print("Done!")


def update_intrinsics(llvm_path):
    files = []
    intrinsics_path = os.path.join(llvm_path, "llvm/include/llvm/IR")
    for (dirpath, dirnames, filenames) in walk(intrinsics_path):
        files.extend([os.path.join(intrinsics_path, f) for f in filenames if f.endswith(".td")])

    intrinsics = {}
    for file in files:
        extract_instrinsics(intrinsics, file)

    archs = [arch for arch in intrinsics]
    archs.sort()
    output_file = os.path.join(
        os.path.dirname(os.path.abspath(__file__)),
        "../src/intrinsic/archs.rs",
    )
    print("Updating content of `{}`...".format(output_file))
    with open(output_file, "w", encoding="utf8") as out:
        out.write("// File generated by `rustc_codegen_gcc/tools/generate_intrinsics.py`\n")
        out.write("// DO NOT EDIT IT!\n")
        out.write("match name {\n")
        for arch in archs:
            if len(intrinsics[arch]) == 0:
                continue
            intrinsics[arch].sort()
            out.write('    // {}\n'.format(arch))
            out.write('\n'.join(['    {}'.format(x) for x in intrinsics[arch]]))
            out.write('\n')
        out.write('    _ => unimplemented!("***** unsupported LLVM intrinsic {}", name),\n')
        out.write("}\n")
    print("Done!")


def main():
    llvm_path = os.path.join(
        os.path.dirname(os.path.abspath(__file__)),
        "llvm-project",
    )

    # First, we clone the LLVM repository if it's not already here.
    clone_repository(
        "llvm-project",
        llvm_path,
        "https://github.com/llvm/llvm-project",
        sub_path="llvm/include/llvm/IR")
    update_intrinsics(llvm_path)


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