// SPDX-License-Identifier: LGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

export module Crafter.Build:Toolchain;
import std;
namespace fs = std::filesystem;

export namespace Crafter {
    // The compiler crafter-build drives and what sits next to it, resolved
    // once per process by GetToolchain(). Every clang++, clang and llvm-ar
    // the tool spawns, the libclang the linter dlopens, the std module
    // source and the default sysroots come from here, so a toolchain
    // installed anywhere other than /usr (the Flatpak carries its own under
    // /app) needs no per-call-site knowledge.
    struct Toolchain {
        // LLVM install prefix. Empty when the tools are bare names on PATH.
        fs::path prefix;
        fs::path clangxx;
        fs::path clang;
        fs::path llvmAr;
        // Where clang-c/Index.h lives when it is not on the default include
        // path; empty otherwise.
        fs::path llvmIncludeDir;
        // The exact libclang to dlopen; nullopt means search the usual names.
        std::optional<fs::path> libclang;
        // A libc++ install other than the compiler's own
        // (CRAFTER_BUILD_LIBCXX_DIR); empty means clang finds its own.
        fs::path libcxxDir;
        // libc++'s std module source for host builds.
        fs::path stdCppm;
        fs::path wasiSysroot;
        // Holds include/c++/<ver>/bits/std.cc for the mingw target. Passed to
        // clang as --sysroot only when it was set explicitly: clang's own
        // mingw discovery handles the distro layout, and a --sysroot pointing
        // at the triple directory would lose crtbegin.o and libgcc.
        fs::path mingwSysroot;
        bool mingwSysrootExplicit = false;
        // `clang++ -print-target-triple` and the first line of
        // `clang++ --version`; both empty when clang++ could not be run.
        std::string hostTriple;
        std::string clangVersion;
        // Why clang++ could not be resolved or run; empty when it could.
        std::string error;

        // Flags for compiling against libcxxDir; empty without one.
        std::string LibcxxCompileFlags() const;
        // Flags for linking against the libc++ the compiler will use: a -L
        // and an rpath for <prefix>/lib when the prefix is not the system one
        // (clang searches only its per-target runtime directory and the
        // system paths, and a bundled toolchain's libc++.so.1 is on neither
        // the linker's nor the loader's default path), or for an explicit
        // libcxxDir.
        std::string LibcxxLinkFlags() const;
        // Names this toolchain for cache directory names: the clang version
        // followed by a hash of what decides which headers and libraries a
        // PCM is built against. Two toolchains with different keys never
        // share a PCM.
        std::string Key() const;
    };

    // What ResolveToolchain reads, so a test can feed it a staged layout.
    struct ToolchainInputs {
        // The CRAFTER_* variables, present only when set and non-empty.
        std::map<std::string, std::string, std::less<>> env;
        // The <prefix> of <prefix>/share/crafter-build; empty when unknown.
        fs::path crafterPrefix;
    };
    // Pure path resolution: an env override wins, then a toolchain installed
    // beside crafter-build (<crafterPrefix>/bin/clang++), then bare names on
    // PATH. Never runs a process, so hostTriple and clangVersion stay empty.
    Toolchain ResolveToolchain(const ToolchainInputs& inputs);
    // ResolveToolchain over the real environment plus the two clang probes,
    // computed once and cached. Never throws.
    const Toolchain& GetToolchain();
    // GetToolchain(), or a std::runtime_error carrying its error.
    const Toolchain& RequireToolchain();
    // The version baked in when crafter-build was built; "0.0.0-dev" for a
    // build that was given none.
    std::string_view CrafterBuildVersion();
}