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

// Every GLSL shader the examples ship still compiles. The examples are
// projects of their own that nothing in this one builds, and crafter-build
// compiles their shaders with whichever glslang it links, unpinned. When
// glslang began rejecting a descriptor_heap combined image sampler (upstream
// c8253623), examples/Sponza stopped building and nothing noticed until it
// was built by hand (#164). This test compiles each examples/<Name>/*.glsl as
// crafter-build does (Vulkan rules, SPIR-V 1.4, shaders/ on the include
// path), with the stage taken from the file name, and a shader that includes
// ui-shared.glsl a second time for the descriptor-set build its example also
// registers. A file whose name gives no stage fails rather than being
// skipped, so a new shader is never silently left out.
//
// Needs glslang on the PATH (a required tool in project.cpp), which need not
// be the glslang crafter-build links, and the source tree, which it finds
// from the build output directory. No GPU.

#include <cstdlib>

import std;

namespace fs = std::filesystem;

namespace {

int failures = 0;

void Check(bool ok, std::string_view what) {
    std::println("{}  {}", ok ? "PASS" : "FAIL", what);
    if (!ok) ++failures;
}

int RunCommand(const std::string& cmd) {
    int status = std::system(cmd.c_str());
    if (status == -1) return -1;
    return (status & 0x7f) == 0 ? ((status >> 8) & 0xff) : 128 + (status & 0x7f);
}

std::string ReadFile(const fs::path& path) {
    std::ifstream in(path, std::ios::binary);
    return {std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>()};
}

// glslang's -S name for the stage, from the file names the examples use:
// raygen.glsl, closesthit.glsl, ..., <name>.comp.glsl. Empty when unknown.
std::string_view StageOf(const fs::path& shader) {
    const std::string stem = shader.stem().string();
    if (stem.ends_with(".comp")) return "comp";
    constexpr std::pair<std::string_view, std::string_view> stages[] = {
        {"raygen", "rgen"}, {"intersection", "rint"}, {"anyhit", "rahit"},
        {"closesthit", "rchit"}, {"miss", "rmiss"},
    };
    for (const auto& [name, stage] : stages) {
        if (stem == name) return stage;
    }
    return {};
}

// The directory holding examples/ and shaders/, whether the test runs from
// its build output directory or the project root, as UIFusedShader finds its
// shader.
fs::path LocateRoot() {
    for (const fs::path candidate : {".", "..", "../..", "../../.."}) {
        std::error_code ec;
        if (fs::is_directory(candidate / "examples", ec)
            && fs::is_regular_file(candidate / "shaders" / "ui-shared.glsl", ec)) {
            return candidate;
        }
    }
    return {};
}

} // namespace

int main() {
    const fs::path root = LocateRoot();
    if (root.empty()) {
        std::println(std::cerr, "could not find examples/ and shaders/ from {}", fs::current_path().string());
        return EXIT_FAILURE;
    }
    const fs::path out = fs::temp_directory_path() / "crafter-example-shaders-test";
    std::error_code ec;
    fs::create_directories(out, ec);

    // Each example's own directory only: its bin/ and build/ hold outputs.
    std::vector<fs::path> shaders;
    for (const fs::directory_entry& example : fs::directory_iterator(root / "examples")) {
        if (!example.is_directory()) continue;
        for (const fs::directory_entry& file : fs::directory_iterator(example.path())) {
            if (file.is_regular_file() && file.path().extension() == ".glsl") shaders.push_back(file.path());
        }
    }
    std::ranges::sort(shaders);
    Check(!shaders.empty(), std::format("found the examples' shaders ({})", shaders.size()));

    for (const fs::path& shader : shaders) {
        const std::string name = (shader.parent_path().filename() / shader.filename()).generic_string();
        const std::string_view stage = StageOf(shader);
        if (stage.empty()) {
            Check(false, std::format("{}: no stage known for this file name; name it after its stage or teach StageOf", name));
            continue;
        }
        // A shader on ui-shared.glsl's UI_HEAP_* macros is registered twice
        // by its example, the second build for drivers without the heap.
        const bool setsBuild = ReadFile(shader).contains("ui-shared.glsl");
        for (const bool sets : {false, true}) {
            if (sets && !setsBuild) continue;
            const std::string base = std::format("{}-{}{}", shader.parent_path().filename().string(),
                                                 shader.stem().string(), sets ? ".sets" : "");
            const fs::path log = out / (base + ".log");
            const std::string compile = std::format(
                "glslang -V --target-env spirv1.4 -S {} {}-I\"{}\" -o \"{}\" \"{}\" > \"{}\" 2>&1",
                stage, sets ? "-DCRAFTER_GRAPHICS_DESCRIPTOR_SETS " : "", (root / "shaders").string(),
                (out / (base + ".spv")).string(), shader.string(), log.string());
            const bool compiled = RunCommand(compile) == 0;
            if (!compiled) std::print("{}", ReadFile(log));
            Check(compiled, std::format("{} compiles{}", name, sets ? " (descriptor-set build)" : ""));
        }
    }

    std::println("{}", failures == 0 ? "all checks passed" : "check(s) failed");
    return failures == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
}