#include <catch2/catch_test_macros.hpp>

import cargoxx.layout;
import cargoxx.util;
import std;

using cargoxx::layout::DiscoveredLayout;
using cargoxx::layout::discover;
using cargoxx::layout::Target;
using cargoxx::layout::TargetKind;
using cargoxx::util::ErrorCode;

namespace {

class TempProject {
  public:
    TempProject() {
        root_ = std::filesystem::temp_directory_path() /
                std::format("cargoxx-layout-test-{}", std::random_device{}());
        std::filesystem::create_directories(root_);
    }

    ~TempProject() {
        std::error_code ec;
        std::filesystem::remove_all(root_, ec);
    }

    TempProject(const TempProject&) = delete;
    TempProject& operator=(const TempProject&) = delete;
    TempProject(TempProject&&) = delete;
    TempProject& operator=(TempProject&&) = delete;

    auto root() const -> const std::filesystem::path& { return root_; }

    auto touch(std::string_view rel) -> std::filesystem::path {
        auto p = root_ / rel;
        std::filesystem::create_directories(p.parent_path());
        std::ofstream{p} << "// stub\n";
        return p;
    }

  private:
    std::filesystem::path root_;
};

} // namespace

TEST_CASE("discover returns LayoutNoTarget for an empty src", "[layout]") {
    TempProject p;
    std::filesystem::create_directories(p.root() / "src");
    auto r = discover(p.root(), "foo");
    REQUIRE_FALSE(r.has_value());
    REQUIRE(r.error().code == ErrorCode::LayoutNoTarget);
}

TEST_CASE("discover finds main.cpp as a binary", "[layout]") {
    TempProject p;
    auto main = p.touch("src/main.cpp");
    auto r = discover(p.root(), "foo");
    REQUIRE(r.has_value());
    REQUIRE_FALSE(r->library.has_value());
    REQUIRE(r->binaries.size() == 1);
    REQUIRE(r->binaries[0].kind == TargetKind::Binary);
    REQUIRE(r->binaries[0].name == "foo");
    REQUIRE(r->binaries[0].entry == main);
}

TEST_CASE("discover finds lib.cppm as a library", "[layout]") {
    TempProject p;
    auto lib = p.touch("src/lib.cppm");
    auto r = discover(p.root(), "foo");
    REQUIRE(r.has_value());
    REQUIRE(r->library.has_value());
    REQUIRE(r->library->kind == TargetKind::Library);
    REQUIRE(r->library->name == "foo");
    REQUIRE(r->library->entry == lib);
    REQUIRE(r->library->module_units == std::vector{lib});
    REQUIRE(r->library->additional_sources.empty());
    REQUIRE(r->binaries.empty());
}

TEST_CASE("discover supports lib + main together", "[layout]") {
    TempProject p;
    p.touch("src/lib.cppm");
    p.touch("src/main.cpp");
    auto r = discover(p.root(), "foo");
    REQUIRE(r.has_value());
    REQUIRE(r->library.has_value());
    REQUIRE(r->binaries.size() == 1);
    REQUIRE(r->binaries[0].entry.filename() == "main.cpp");
}

TEST_CASE("discover collects nested .cppm and .cpp into the library",
          "[layout]") {
    TempProject p;
    auto lib = p.touch("src/lib.cppm");
    auto inner_cppm = p.touch("src/internal/foo.cppm");
    auto inner_cpp = p.touch("src/internal/foo.cpp");
    auto r = discover(p.root(), "foo");
    REQUIRE(r.has_value());
    REQUIRE(r->library->module_units.size() == 2);
    REQUIRE(std::ranges::find(r->library->module_units, lib) !=
            r->library->module_units.end());
    REQUIRE(std::ranges::find(r->library->module_units, inner_cppm) !=
            r->library->module_units.end());
    REQUIRE(r->library->additional_sources == std::vector{inner_cpp});
}

TEST_CASE("discover excludes src/bin/* from the library walk", "[layout]") {
    TempProject p;
    p.touch("src/lib.cppm");
    p.touch("src/bin/tool.cpp");
    auto r = discover(p.root(), "foo");
    REQUIRE(r.has_value());
    REQUIRE(r->library->additional_sources.empty());
    REQUIRE(r->binaries.size() == 1);
    REQUIRE(r->binaries[0].name == "tool");
}

TEST_CASE("discover lists src/bin/*.cpp as additional binaries", "[layout]") {
    TempProject p;
    p.touch("src/main.cpp");
    p.touch("src/bin/foo.cpp");
    p.touch("src/bin/bar.cpp");
    auto r = discover(p.root(), "pkg");
    REQUIRE(r.has_value());
    REQUIRE(r->binaries.size() == 3);
    // sorted alphabetically by target name
    REQUIRE(r->binaries[0].name == "bar");
    REQUIRE(r->binaries[1].name == "foo");
    REQUIRE(r->binaries[2].name == "pkg");
}

TEST_CASE("discover ignores src/bin/<sub>/ subdirs without main.cpp", "[layout]") {
    TempProject p;
    p.touch("src/main.cpp");
    p.touch("src/bin/foo.cpp");
    p.touch("src/bin/sub/nested.cpp"); // no main.cpp at sub/ root, ignored
    auto r = discover(p.root(), "pkg");
    REQUIRE(r.has_value());
    REQUIRE(r->binaries.size() == 2);
}

TEST_CASE("discover lists src/bin/<sub>/main.cpp as a binary named <sub>",
           "[layout]") {
    TempProject p;
    p.touch("src/main.cpp");
    p.touch("src/bin/extra/main.cpp");
    p.touch("src/bin/extra/helpers.cpp"); // not collected in v1
    auto r = discover(p.root(), "pkg");
    REQUIRE(r.has_value());
    REQUIRE(r->binaries.size() == 2);
    REQUIRE(r->binaries[0].name == "extra");
    REQUIRE(r->binaries[0].entry.filename() == "main.cpp");
    REQUIRE(r->binaries[0].entry.parent_path().filename() == "extra");
    REQUIRE(r->binaries[1].name == "pkg");
}

TEST_CASE("discover lists tests/*.cpp", "[layout]") {
    TempProject p;
    p.touch("src/main.cpp");
    p.touch("tests/alpha.cpp");
    p.touch("tests/beta.cpp");
    p.touch("tests/sub/nested.cpp"); // ignored, no recursion
    auto r = discover(p.root(), "pkg");
    REQUIRE(r.has_value());
    REQUIRE(r->tests.size() == 2);
    REQUIRE(r->tests[0].name == "alpha");
    REQUIRE(r->tests[0].kind == TargetKind::Test);
    REQUIRE(r->tests[1].name == "beta");
}

TEST_CASE("discover lists examples/*.cpp", "[layout]") {
    TempProject p;
    p.touch("src/main.cpp");
    p.touch("examples/demo.cpp");
    auto r = discover(p.root(), "pkg");
    REQUIRE(r.has_value());
    REQUIRE(r->examples.size() == 1);
    REQUIRE(r->examples[0].name == "demo");
    REQUIRE(r->examples[0].kind == TargetKind::Example);
}

TEST_CASE("discover ignores non .cpp/.cppm files", "[layout]") {
    TempProject p;
    p.touch("src/main.cpp");
    p.touch("src/notes.txt");
    p.touch("src/lib.cppm");
    p.touch("src/internal/header.h"); // headers in src/ are ignored
    auto r = discover(p.root(), "pkg");
    REQUIRE(r.has_value());
    REQUIRE(r->library->module_units.size() == 1);
    REQUIRE(r->library->additional_sources.empty());
}

TEST_CASE("discover output is deterministic across runs", "[layout]") {
    TempProject p;
    p.touch("src/lib.cppm");
    p.touch("src/zeta.cppm");
    p.touch("src/alpha.cppm");
    p.touch("src/middle.cppm");
    auto r1 = discover(p.root(), "pkg");
    auto r2 = discover(p.root(), "pkg");
    REQUIRE(r1.has_value());
    REQUIRE(r2.has_value());
    REQUIRE(*r1 == *r2);
    REQUIRE(std::ranges::is_sorted(r1->library->module_units));
}