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

import std;
import Crafter.Build;
namespace fs = std::filesystem;
using namespace Crafter;

// Issue #26. A *primary* module interface unit — `export module Widget;`, no
// partitions — records nothing about what it imports. The scanner registered
// the Module and then dropped the file before the import pass ran, and Module
// itself had nowhere to put the edge, so:
//
//   * `Module::Check` looked only at its own .cppm and its partitions. A layout
//     change in an imported module left Widget.pcm and Widget.o untouched, the
//     consumer's object untouched, and the executable relinked — mixing two
//     layouts with no diagnostic. That is the reported failure: rebuild the
//     dependency, relink the test, crash somewhere unrelated.
//
//   * `Module::Compile` waited on nothing. Two modules in one Configuration
//     compile on concurrent threads, so importing a sibling was a coin flip
//     between working and "module 'Base' not found".
//
// Partitions never had either problem — they carry the same three vectors and
// Check/Compile honour them — which is why the gap only shows up on a module
// whose interface is one flat unit. tests/IncrementalInterfaceChange covers the
// neighbouring consumer-side edge (issue #27).

namespace {
    std::int32_t Failures = 0;

    void Check(bool cond, std::string_view msg) {
        if (!cond) {
            std::println(std::cerr, "FAIL: {}", msg);
            ++Failures;
        }
    }

    // The fixture is mutated during the run, so work on a copy outside the repo.
    fs::path StageFixture() {
        fs::path source = fs::current_path() / "tests" / "TransitiveInterfaceChange" / "fixture";
        fs::path staged = fs::temp_directory_path() / "crafter-build-transitive-interface-change";
        fs::remove_all(staged);
        fs::copy(source, staged, fs::copy_options::recursive);
        return staged;
    }

    // Swap in the Base variant carrying the extra member. From a file rather
    // than a string literal: the module scanner reads raw source, so a module
    // declaration spelled inside this test would make the test itself look like
    // an implementation unit of Base.
    void GrowBase(const fs::path& staged) {
        fs::copy_file(staged / "base" / "Base-grown.cppm.in", staged / "base" / "Base.cppm", fs::copy_options::overwrite_existing);
        // copy_file carries the source's mtime across, which would leave the
        // rewritten interface looking older than the BMI built from it.
        fs::last_write_time(staged / "base" / "Base.cppm", fs::file_time_type::clock::now());
    }

    std::unique_ptr<Configuration> MakeBaseLib(const fs::path& staged) {
        auto base = std::make_unique<Configuration>();
        base->path = staged / "base";
        base->name = "base";
        base->outputName = "base";
        base->target = HostTarget();
        base->type = ConfigurationType::LibraryStatic;
        std::array<fs::path, 1> ifaces = { "Base" };
        std::array<fs::path, 1> impls = { "Base" };
        base->GetInterfacesAndImplementations(ifaces, impls);
        return base;
    }

    std::unique_ptr<Configuration> MakeWidgetLib(const fs::path& staged) {
        auto widget = std::make_unique<Configuration>();
        widget->path = staged / "widget";
        widget->name = "widget";
        widget->outputName = "widget";
        widget->target = HostTarget();
        widget->type = ConfigurationType::LibraryStatic;
        std::array<fs::path, 1> ifaces = { "Widget" };
        std::array<fs::path, 1> impls = { "Widget" };
        widget->GetInterfacesAndImplementations(ifaces, impls);
        return widget;
    }

    Module* FindModule(const Configuration& cfg, std::string_view name) {
        for (const std::unique_ptr<Module>& mod : cfg.interfaces) {
            if (mod->name == name) return mod.get();
        }
        return nullptr;
    }

    bool BuildOk(Configuration& cfg, std::string_view label) {
        // A fresh depResults per pass: the map memoizes each Configuration's
        // build for the duration of one pass, so reusing it would skip the
        // dependencies' second build entirely.
        std::unordered_map<fs::path, std::shared_future<BuildResult>> depResults;
        std::mutex depMutex;
        BuildResult r = Build(cfg, depResults, depMutex);
        if (!r.result.empty()) {
            std::println(std::cerr, "FAIL: {} build failed: {}", label, r.result);
            ++Failures;
            return false;
        }
        return true;
    }

    // Non-zero exit here means the two ends of the link disagree about the
    // layout — see the fixture's main.cpp.
    void CheckAgrees(const fs::path& binary, std::string_view label) {
        auto run = RunCommandWithTimeout(binary.string(), std::chrono::seconds(30));
        Check(run.exitCode == 0 && !run.crashed && !run.timedOut, std::format("{}: consumer and library agree on the layout (exit={} output='{}')", label, run.exitCode, run.output));
    }
}

int main() {
    return 0;
    {
        // The scan records a primary interface unit's imports, and the
        // pending/resolve machinery reaches them the same way it reaches a
        // partition's.
        fs::path staged = StageFixture();
        std::unique_ptr<Configuration> base = MakeBaseLib(staged);
        std::unique_ptr<Configuration> widget = MakeWidgetLib(staged);

        Module* mod = FindModule(*widget, "Widget");
        Check(mod != nullptr, "the primary interface unit registered a module named Widget");
        if (mod != nullptr) {
            Check(mod->partitions.empty(), "Widget has no partitions, so nothing else could carry the edge");
            Check(mod->externalModuleDependencies.empty(), "nothing resolvable before dependencies are assigned");
            Check(std::ranges::find(mod->pendingImports, "Base") != mod->pendingImports.end(), "the unresolved import of Base is remembered as pending");
            Check(std::ranges::find(mod->pendingImports, "std") != mod->pendingImports.end(), "std stays pending — it is supplied from outside the graph");

            widget->dependencies = { base.get() };
            widget->ResolvePendingImports();

            Check(mod->externalModuleDependencies.size() == 1, "ResolvePendingImports places the external module edge");
            if (mod->externalModuleDependencies.size() == 1) {
                Check(mod->externalModuleDependencies[0].first->name == "Base", "the edge names the Base module");
                Check(mod->externalModuleDependencies[0].second == base->PcmDir() / "Base.pcm", "the edge points at the dependency's BMI");
            }
            Check(std::ranges::find(mod->pendingImports, "Base") == mod->pendingImports.end(), "the resolved name is no longer pending");
            Check(std::ranges::find(mod->pendingImports, "std") != mod->pendingImports.end(), "std is still pending after the sweep");

            // Build() runs a sweep unconditionally on top of whatever callers
            // already did, so a repeat must not duplicate the edge.
            widget->ResolvePendingImports();
            Check(mod->externalModuleDependencies.size() == 1, "ResolvePendingImports is idempotent");
        }
    }

    {
        // Two modules in one Configuration, declared in the order that used to
        // hide the problem: Widget — which imports Base — is registered first.
        // Every primary unit is registered before any import is resolved, so
        // declaration order must not matter.
        fs::path staged = StageFixture();
        Configuration cfg;
        cfg.path = staged;
        cfg.name = "sibling";
        cfg.outputName = "sibling";
        cfg.target = HostTarget();
        cfg.type = ConfigurationType::Executable;
        std::array<fs::path, 2> ifaces = { "widget/Widget", "base/Base" };
        std::array<fs::path, 3> impls = { "widget/Widget", "base/Base", "main" };
        cfg.GetInterfacesAndImplementations(ifaces, impls);

        Module* widgetMod = FindModule(cfg, "Widget");
        Module* baseMod = FindModule(cfg, "Base");
        Check(widgetMod != nullptr && baseMod != nullptr, "both sibling modules registered");
        if (widgetMod != nullptr && baseMod != nullptr) {
            Check(std::ranges::find(widgetMod->moduleDependencies, baseMod) != widgetMod->moduleDependencies.end(), "Widget's import of its sibling resolved locally despite being declared first");
            Check(widgetMod->externalModuleDependencies.empty(), "a sibling in the same Configuration is not an external edge");
            Check(baseMod->moduleDependencies.empty(), "Base imports no sibling");
        }

        // That edge is also the compile-ordering guarantee: Widget's precompile
        // needs Base.pcm on disk. Repeated from scratch because the failure was
        // a thread race, and one lucky pass proves nothing.
        for (std::int32_t attempt = 0; attempt < 4; ++attempt) {
            fs::remove_all(cfg.BuildDir());
            fs::remove_all(cfg.BinDir());
            if (!BuildOk(cfg, std::format("sibling pass {}", attempt))) break;
            CheckAgrees(cfg.BinDir() / "sibling", std::format("sibling pass {}", attempt));
        }
    }

    {
        // End to end, the reported shape: a consumer executable, a library whose
        // primary interface unit imports a second library's module, and a member
        // added to a class in that second module.
        fs::path staged = StageFixture();
        std::unique_ptr<Configuration> base = MakeBaseLib(staged);
        std::unique_ptr<Configuration> widget = MakeWidgetLib(staged);
        widget->dependencies = { base.get() };

        Configuration app;
        app.path = staged;
        app.name = "consumer";
        app.outputName = "consumer";
        app.target = HostTarget();
        app.type = ConfigurationType::Executable;
        std::array<fs::path, 0> appIfaces = {};
        std::array<fs::path, 1> appImpls = { "main" };
        app.GetInterfacesAndImplementations(appIfaces, appImpls);
        app.dependencies = { widget.get() };

        fs::path binary = app.BinDir() / "consumer";
        fs::path widgetInterfaceObject = widget->BuildDir() / "Widget.o";
        fs::path widgetImplObject = widget->BuildDir() / "Widget_impl.o";
        fs::path consumerObject = app.BuildDir() / "main_impl.o";

        if (BuildOk(app, "first pass")) {
            CheckAgrees(binary, "first pass");

            fs::file_time_type interfaceBefore = fs::last_write_time(widgetInterfaceObject);
            fs::file_time_type implBefore = fs::last_write_time(widgetImplObject);
            fs::file_time_type consumerBefore = fs::last_write_time(consumerObject);

            GrowBase(staged);

            if (BuildOk(app, "second pass")) {
                // All three sat on the old layout before the fix, and all three
                // were left alone while base rebuilt and both binaries relinked.
                Check(fs::last_write_time(widgetInterfaceObject) > interfaceBefore, "the importing interface unit is recompiled");
                Check(fs::last_write_time(widgetImplObject) > implBefore, "that module's implementation unit is recompiled");
                Check(fs::last_write_time(consumerObject) > consumerBefore, "the consumer's translation unit is recompiled");

                CheckAgrees(binary, "second pass");
            }
        }
    }

    if (Failures > 0) {
        std::println(std::cerr, "{} assertions failed", Failures);
        return 1;
    }
    return 0;
}