#include <gtest/gtest.h>
#include "package_manager_lib.h"
#include <lgx.h>
#include <algorithm>
#include <filesystem>
#include <fstream>
#include <string>
#include <vector>

namespace fs = std::filesystem;

namespace {

/**
 * RAII for the process-wide platform override.
 *
 * platformVariantOverride() is a plain global, so a test that pretends to be
 * another host has to put it back or it leaks into every later test in this
 * binary. Restoring the PREVIOUS value rather than "" keeps these tests
 * composable with a caller that set one.
 */
class ScopedPlatformOverride {
public:
    explicit ScopedPlatformOverride(const std::string& variant)
        : m_previous(PackageManagerLib::platformVariantOverride())
    {
        PackageManagerLib::setPlatformVariantOverride(variant);
    }
    ~ScopedPlatformOverride() { PackageManagerLib::setPlatformVariantOverride(m_previous); }

private:
    std::string m_previous;
};

/**
 * A non-portable build appends "-dev" to every accepted variant and a portable
 * one does not. LGPM_PORTABLE_BUILD is a PRIVATE compile definition of
 * package_manager_lib, so the test binary cannot read it -- accept either
 * spelling instead of guessing which build this is.
 */
bool accepts(const std::vector<std::string>& variants, const std::string& bare)
{
    return std::find(variants.begin(), variants.end(), bare) != variants.end()
        || std::find(variants.begin(), variants.end(), bare + "-dev") != variants.end();
}

std::string join(const std::vector<std::string>& v)
{
    std::string out;
    for (const auto& s : v) {
        if (!out.empty()) out += ", ";
        out += s;
    }
    return "[" + out + "]";
}

} // namespace

// =============================================================================
// Shape of the host's own variant
// =============================================================================

TEST(VariantTest, CurrentPlatformVariantNotEmpty) {
    std::string variant = PackageManagerLib::currentPlatformVariant();
    EXPECT_FALSE(variant.empty());
    EXPECT_NE(variant, "unknown");
}

TEST(VariantTest, CurrentPlatformVariantFormat) {
    std::string variant = PackageManagerLib::currentPlatformVariant();
    // Should contain a dash separating OS and arch
    EXPECT_NE(variant.find('-'), std::string::npos);
}

TEST(VariantTest, PlatformVariantsToTryNotEmpty) {
    auto variants = PackageManagerLib::platformVariantsToTry();
    EXPECT_FALSE(variants.empty());
}

TEST(VariantTest, HostOwnVariantIsAlwaysFirst) {
    // The head of the list is what diagnostics print as "this machine", and
    // what test helpers elsewhere in this suite use to build a package the
    // host will accept. Aliasing must widen the tail, never displace the head.
    const std::string primary = PackageManagerLib::currentPlatformVariant();
    auto variants = PackageManagerLib::platformVariantsToTry();
    ASSERT_FALSE(variants.empty());
    EXPECT_EQ(variants.front().rfind(primary, 0), 0u)
        << "first entry " << variants.front() << " does not start with " << primary;
}

// =============================================================================
// Producer/consumer spelling agreement
//
// This is a TABLE over every target this ecosystem ships, not a probe of the
// host, because the defect being pinned is invisible from any single host: an
// arm64 Mac never computes darwin-x86_64 and so never meets it.
//
// Left column is what a host computes for itself (currentPlatformVariant);
// right column is a spelling some producer actually writes into a .lgx, so it
// has to resolve on that host. The producers disagree with EACH OTHER --
//
//   nix-bundle-lgx/flake.nix:52                  darwin-amd64  linux-amd64
//                                                darwin-arm64  linux-arm64
//   nix-bundle-logos-module-install/flake.nix:49 darwin-x86_64 linux-x86_64
//                                                darwin-arm64  linux-arm64
//
// -- and the second CONSUMES the first, calling lgpm --platform with its own
// spelling on a package the first named. So both columns must resolve here.
// =============================================================================

namespace {
struct VariantAliasCase {
    const char* host;          // what currentPlatformVariant() would return
    const char* alsoAccepted;  // a producer spelling that must still resolve
};

const VariantAliasCase kAliasCases[] = {
    // linux: bridged before this change
    { "linux-x86_64",   "linux-amd64"     },
    { "linux-amd64",    "linux-x86_64"    },
    { "linux-arm64",    "linux-aarch64"   },
    { "linux-aarch64",  "linux-arm64"     },
    // darwin: NOT bridged before this change. The first row is the reported
    // Intel-Mac failure -- nix-bundle-lgx writes darwin-amd64, lgpm computes
    // darwin-x86_64, and install refuses.
    { "darwin-x86_64",  "darwin-amd64"    },
    { "darwin-amd64",   "darwin-x86_64"   },
    { "darwin-arm64",   "darwin-aarch64"  },
    { "darwin-aarch64", "darwin-arm64"    },
    // windows: NOT bridged before this change, and its producer spelling is
    // the odd one out (windows-x86_64 where the same producer writes
    // linux-amd64), which is exactly the per-OS exception that caused this.
    { "windows-x86_64", "windows-amd64"   },
    { "windows-amd64",  "windows-x86_64"  },
    { "windows-arm64",  "windows-aarch64" },
    { "windows-aarch64","windows-arm64"   },
};
} // namespace

TEST(VariantTest, EveryTargetAcceptsBothArchSpellings) {
    for (const auto& c : kAliasCases) {
        ScopedPlatformOverride guard(c.host);
        auto variants = PackageManagerLib::platformVariantsToTry();
        EXPECT_TRUE(accepts(variants, c.host))
            << "host " << c.host << " does not accept its own spelling; got " << join(variants);
        EXPECT_TRUE(accepts(variants, c.alsoAccepted))
            << "host " << c.host << " does not accept producer spelling "
            << c.alsoAccepted << "; got " << join(variants);
    }
}

// =============================================================================
// Fail-closed guarantees. Aliasing must WIDEN within one target and never
// across targets: a Windows package on a Mac, or an arm64 package on an x86_64
// host, must still be refused.
// =============================================================================

TEST(VariantTest, NeverAcceptsAnotherOperatingSystem) {
    const char* const hosts[] = { "darwin-x86_64", "darwin-arm64", "linux-x86_64",
                                  "linux-arm64", "windows-x86_64" };
    const char* const foreign[] = { "darwin-x86_64", "darwin-amd64", "darwin-arm64",
                                    "darwin-aarch64", "linux-x86_64", "linux-amd64",
                                    "linux-arm64", "linux-aarch64", "windows-x86_64",
                                    "windows-amd64", "windows-arm64", "windows-aarch64" };
    for (const char* host : hosts) {
        ScopedPlatformOverride guard(host);
        auto variants = PackageManagerLib::platformVariantsToTry();
        const std::string hostOs = std::string(host).substr(0, std::string(host).rfind('-'));
        for (const char* f : foreign) {
            const std::string fOs = std::string(f).substr(0, std::string(f).rfind('-'));
            if (fOs == hostOs) continue;
            EXPECT_FALSE(accepts(variants, f))
                << "host " << host << " accepted foreign-OS variant " << f
                << "; got " << join(variants);
        }
    }
}

TEST(VariantTest, NeverAcceptsAnotherArchitecture) {
    struct { const char* host; const char* foreignArch; } cases[] = {
        { "darwin-x86_64",  "darwin-arm64"    },
        { "darwin-x86_64",  "darwin-aarch64"  },
        { "darwin-arm64",   "darwin-x86_64"   },
        { "darwin-arm64",   "darwin-amd64"    },
        { "linux-x86_64",   "linux-arm64"     },
        { "linux-arm64",    "linux-amd64"     },
        { "windows-x86_64", "windows-arm64"   },
    };
    for (const auto& c : cases) {
        ScopedPlatformOverride guard(c.host);
        auto variants = PackageManagerLib::platformVariantsToTry();
        EXPECT_FALSE(accepts(variants, c.foreignArch))
            << "host " << c.host << " accepted foreign-arch variant " << c.foreignArch
            << "; got " << join(variants);
    }
}

TEST(VariantTest, UnknownArchitectureGetsNoAliasesAndStillNamesItself) {
    // A spelling no table row knows must degrade to "itself only" rather than
    // throwing away the host's own variant.
    ScopedPlatformOverride guard("linux-riscv64");
    auto variants = PackageManagerLib::platformVariantsToTry();
    EXPECT_TRUE(accepts(variants, "linux-riscv64")) << join(variants);
    EXPECT_EQ(variants.size(), 1u) << join(variants);
}

TEST(VariantTest, OverrideIsRestoredAfterScopedUse) {
    const std::string before = PackageManagerLib::currentPlatformVariant();
    {
        ScopedPlatformOverride guard("windows-arm64");
        EXPECT_EQ(PackageManagerLib::currentPlatformVariant(), "windows-arm64");
    }
    EXPECT_EQ(PackageManagerLib::currentPlatformVariant(), before);
}

// =============================================================================
// End-to-end: a real .lgx, built with a producer's spelling, installed by a
// host that computes the other spelling.
//
// The unit assertions above pin the accept LIST; these pin what the list is
// for. They are also the backward-compatibility proof: every variant name
// exercised here is one that already exists in published packages
// (darwin-arm64, linux-amd64, linux-arm64) or that the standard bundler emits
// on a target it has never been able to ship (darwin-amd64).
// =============================================================================

class VariantInstallTest : public ::testing::Test {
protected:
    fs::path tempDir;
    fs::path modulesDir;
    fs::path uiPluginsDir;

    void SetUp() override {
        tempDir = fs::temp_directory_path()
                / ("lgpm_variant_test_" + std::to_string(::testing::UnitTest::GetInstance()
                                                             ->random_seed())
                   + "_" + std::to_string(std::rand()));
        modulesDir = tempDir / "modules";
        uiPluginsDir = tempDir / "ui_plugins";
        fs::create_directories(modulesDir);
        fs::create_directories(uiPluginsDir);
    }

    void TearDown() override {
        std::error_code ec;
        fs::remove_all(tempDir, ec);
    }

    /**
     * Build a real .lgx whose only variant is the one the given PRODUCER host
     * would name for itself -- i.e. platformVariantsToTry().front() evaluated
     * under that host, which carries the build's own -dev/portable suffix.
     */
    fs::path createPackageAsProducedBy(const std::string& name,
                                       const std::string& producerHost) {
        std::string variant;
        {
            ScopedPlatformOverride guard(producerHost);
            auto v = PackageManagerLib::platformVariantsToTry();
            if (v.empty()) return {};
            variant = v.front();
        }

        fs::path lgxPath = tempDir / (name + ".lgx");
        fs::path contentDir = tempDir / (name + "_content");
        fs::create_directories(contentDir);

#if defined(__APPLE__)
        std::string libName = name + "_plugin.dylib";
#elif defined(_WIN32)
        std::string libName = name + "_plugin.dll";
#else
        std::string libName = name + "_plugin.so";
#endif
        { std::ofstream f(contentDir / libName); f << "fake library content"; }
        {
            std::ofstream mf(contentDir / "manifest.json");
            mf << "{\n  \"name\": \"" << name << "\",\n"
               << "  \"version\": \"1.0.0\",\n"
               << "  \"type\": \"core\",\n"
               << "  \"category\": \"test\"\n}";
        }

        lgx_result_t res = lgx_create(lgxPath.string().c_str(), name.c_str());
        if (!res.success) return {};
        lgx_package_t pkg = lgx_load(lgxPath.string().c_str());
        if (!pkg) return {};
        res = lgx_add_variant(pkg, variant.c_str(), contentDir.string().c_str(),
                              libName.c_str());
        if (!res.success) { lgx_free_package(pkg); return {}; }
        res = lgx_save(pkg, lgxPath.string().c_str());
        lgx_free_package(pkg);
        if (!res.success) return {};
        return lgxPath;
    }

    PackageManagerLib createPM() {
        PackageManagerLib pm;
        pm.setUserModulesDirectory(modulesDir.string());
        pm.setUserUiPluginsDirectory(uiPluginsDir.string());
        pm.setSignaturePolicy(SignaturePolicy::WARN);
        return pm;
    }
};

TEST_F(VariantInstallTest, IntelMacInstallsAPackageTheStandardBundlerProduced) {
    // nix-bundle-lgx names an x86_64-darwin build "darwin-amd64"; an Intel Mac
    // computes "darwin-x86_64". This is the reported failure, end to end.
    auto lgxPath = createPackageAsProducedBy("bundler_pkg", "darwin-amd64");
    ASSERT_FALSE(lgxPath.empty());

    ScopedPlatformOverride host("darwin-x86_64");
    auto pm = createPM();
    std::string errorMsg;
    std::string result = pm.installPluginFile(lgxPath.string(), errorMsg);
    ASSERT_FALSE(result.empty()) << errorMsg;
    // installPluginFile returns the directory it installed INTO; the package's
    // own manifest decides whether that is the module or the ui-plugin dir.
    EXPECT_TRUE(fs::exists(fs::path(result) / "bundler_pkg")) << result;
}

TEST_F(VariantInstallTest, PublishedSpellingsStillInstall) {
    // Every variant name live in the registry today, each installed by the
    // host that computes the OTHER spelling for the same target. Nothing here
    // may regress: 15 published packages / 146 manifest rows use these names.
    struct { const char* pkg; const char* producer; const char* host; } cases[] = {
        { "pub_darwin_arm64", "darwin-arm64", "darwin-aarch64" },
        { "pub_linux_amd64",  "linux-amd64",  "linux-x86_64"   },
        { "pub_linux_arm64",  "linux-arm64",  "linux-aarch64"  },
    };
    for (const auto& c : cases) {
        auto lgxPath = createPackageAsProducedBy(c.pkg, c.producer);
        ASSERT_FALSE(lgxPath.empty()) << c.pkg;

        ScopedPlatformOverride host(c.host);
        auto pm = createPM();
        std::string errorMsg;
        std::string result = pm.installPluginFile(lgxPath.string(), errorMsg);
        EXPECT_FALSE(result.empty())
            << c.producer << " package refused by host " << c.host << ": " << errorMsg;
        if (result.empty()) continue;   // report every row, don't stop at the first
        EXPECT_TRUE(fs::exists(fs::path(result) / c.pkg)) << result;
    }
}

TEST_F(VariantInstallTest, SameSpellingStillInstalls) {
    // The null-change control: producer and host agree, which worked before
    // this change and must keep working.
    struct { const char* pkg; const char* both; } cases[] = {
        { "same_darwin_arm64", "darwin-arm64"  },
        { "same_linux_amd64",  "linux-amd64"   },
        { "same_darwin_x8664", "darwin-x86_64" },
    };
    for (const auto& c : cases) {
        auto lgxPath = createPackageAsProducedBy(c.pkg, c.both);
        ASSERT_FALSE(lgxPath.empty()) << c.pkg;

        ScopedPlatformOverride host(c.both);
        auto pm = createPM();
        std::string errorMsg;
        std::string result = pm.installPluginFile(lgxPath.string(), errorMsg);
        EXPECT_FALSE(result.empty()) << c.both << ": " << errorMsg;
        if (result.empty()) continue;   // report every row, don't stop at the first
        EXPECT_TRUE(fs::exists(fs::path(result) / c.pkg)) << result;
    }
}

TEST_F(VariantInstallTest, ForeignTargetPackagesAreStillRefused) {
    // Widening the accept set must not have opened a cross-target hole.
    struct { const char* pkg; const char* producer; const char* host; } cases[] = {
        { "foreign_os",   "windows-x86_64", "darwin-x86_64" },
        { "foreign_arch", "darwin-arm64",   "darwin-x86_64" },
        { "foreign_both", "linux-amd64",    "darwin-arm64"  },
    };
    for (const auto& c : cases) {
        auto lgxPath = createPackageAsProducedBy(c.pkg, c.producer);
        ASSERT_FALSE(lgxPath.empty()) << c.pkg;

        ScopedPlatformOverride host(c.host);
        auto pm = createPM();
        std::string errorMsg;
        std::string result = pm.installPluginFile(lgxPath.string(), errorMsg);
        EXPECT_TRUE(result.empty())
            << c.producer << " package was installed on host " << c.host;
        EXPECT_NE(errorMsg.find("variant"), std::string::npos) << errorMsg;
        EXPECT_FALSE(fs::exists(modulesDir / c.pkg));
        EXPECT_FALSE(fs::exists(uiPluginsDir / c.pkg));
    }
}