/*
Crafter® Build
Copyright (C) 2026 Catcrafts®
Catcrafts.net

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License version 3.0 as published by the Free Software Foundation;

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
*/

module;
#include "Crafter.Build-Api.h"
export module Crafter.Build:Clang;
import std;
import :Shader;
import :Interface;
import :Implementation;
import :External;
namespace fs = std::filesystem;

export namespace Crafter {
    struct BuildResult {
        std::string result;
        bool repack;
        std::unordered_set<std::string> libs;
        // Compile flags (typically -I include paths) the dep wants its
        // consumers to see — sourced from its external dependencies' include
        // dirs so headers a dep exposes in its public modules are reachable
        // when a consumer #includes them directly. Propagates transitively.
        std::unordered_set<std::string> publicCompileFlags;
    };

    struct Define {
        std::string name;
        std::string value;
    };

    // A browser-wasm codegen variant. The same wasm32 target is compiled more
    // than once, each pass adding `flags` to every translation unit, so newer
    // ISA features (relaxed SIMD today; threads, future SIMD revisions, … later)
    // can be adopted without dropping engines that lack them. Each non-empty
    // `label` emits an additional `outputName.<label>.wasm` alongside the
    // baseline `outputName.wasm`; `probes` names the runtime feature-detect
    // checks (see wasi-runtime/runtime.js's probe registry) that must all pass
    // for a browser to be served this variant. The first variant whose probes
    // pass wins; the baseline is the universal fallback.
    struct WasmVariant {
        std::string label;
        std::vector<std::string> flags;
        std::vector<std::string> probes;
    };

    enum class ConfigurationType {
        Executable,
        LibraryStatic,
        LibraryDynamic,
    };

    struct Test;

    struct TestRunner {
        // Command template the harness executes to run the test binary.
        // Local runners leave this empty; prefix runners (Cmd, Wine) set it to
        // a template like "wine {bin} {args}" or "qemu-aarch64 {bin} {args}".
        std::string exec;
        // Display name; also the cache key for the availability probe.
        std::string name;
        // Runs once per RunTests invocation (cached by `name`). Exit 0 = runner
        // is available; non-zero = skip every Test using this runner with a
        // "runner unavailable" message. Empty = always available (e.g., Local).
        std::string probe;

        bool IsLocal() const { return exec.empty(); }

        static CRAFTER_API TestRunner Local();
        // Prefix runner: wraps the local binary in `<command> {bin} {args}`.
        // Used for qemu-user, wasmtime, and similar single-binary wrappers.
        static CRAFTER_API TestRunner Cmd(std::string command);
        // Run a Windows .exe through Wine. Probes `wine` on PATH; on a Windows
        // host the wine wrapper is pointless, so callers should route to Local
        // before reaching here.
        static CRAFTER_API TestRunner Wine();
        // Parse a `<kind>[:<arg>]` spec used by CRAFTER_BUILD_RUNNER_<target>
        // and --runner=. Supported: "local", "cmd:<binary>". Returns nullopt
        // for an empty string; throws on a non-empty unrecognized spec.
        static CRAFTER_API std::optional<TestRunner> FromSpec(std::string_view spec);
        // Honor CRAFTER_BUILD_RUNNER_<target> (power-user override). Triple
        // dashes/dots become underscores so they're valid in env-var names.
        // Returns `fallback` when the env var is unset.
        static CRAFTER_API TestRunner FromEnv(std::string_view target, TestRunner fallback = Local());
        // Derive a runner from a Configuration's target triple + sysroot.
        // Returns Local() when target equals the host, Wine() for Windows
        // targets on a non-Windows host, `qemu-<arch>` (with QEMU_LD_PREFIX
        // set when cfg.sysroot is non-empty) for non-host -linux- triples,
        // `wasmtime` for wasm32-wasi/wasm64-wasi, and Local() as a last
        // resort. CRAFTER_BUILD_RUNNER_<target> still wins as an override
        // upstream of this — see FromEnv.
        static CRAFTER_API TestRunner ForTarget(const struct Configuration& cfg);
    };

    enum class TestOutcome { Pass, Fail, Crash, Timeout, Skipped };

    struct TestResult {
        std::string name;
        TestOutcome outcome = TestOutcome::Pass;
        int exitCode = 0;
        int signal = 0;
        std::chrono::milliseconds duration{0};
        std::string output;
    };

    // The host target triple, detected once per process by running
    // `clang++ -print-target-triple` and cached. Used as the default for
    // Configuration::target so projects don't have to hardcode it for the
    // no-cross-compile case. Returns "" if clang isn't on PATH or doesn't
    // print a triple — those projects still need an explicit cfg.target.
    CRAFTER_API std::string HostTarget();

    struct Configuration {
        fs::path path;
        std::string outputName;
        std::string name;
        std::string march = "native";
        std::string mtune = "native";
        std::string target = HostTarget();
        std::string sysroot;
        bool debug = false;
        ConfigurationType type = ConfigurationType::Executable;
        std::vector<std::unique_ptr<Module>> interfaces;
        std::vector<Implementation> implementations;
        std::vector<fs::path> cFiles;
        std::vector<fs::path> cuda;
        std::vector<Configuration*> dependencies;
        std::vector<fs::path> files;
        // Build-time-only source files this configuration exposes to its own
        // and its consumers' shader compiles as glslang #include search
        // paths. Each entry's parent directory (or the entry itself, if it's
        // a directory) is added to the includer for every shader compiled in
        // this configuration and in any configuration that transitively
        // depends on it. Files are NOT copied — they're read in place from
        // the dep's source tree, like C++ -I include dirs.
        std::vector<fs::path> buildFiles;
        std::vector<Define> defines;
        std::vector<Shader> shaders;
        // Source assets compressed via Crafter.Asset's SaveCompressed →
        // .ctex/.cmesh in this configuration's bin dir.
        //
        // Each entry is either:
        //   - A single .png/.obj file. Output lands flat in the bin dir:
        //     bin/<filename>.ctex or bin/<filename>.cmesh.
        //   - A directory. The build recurses; .png/.obj are compressed
        //     with the relative tree mirrored under bin/<dirname>/, and
        //     every other file in the tree is copied through unchanged.
        //     Lets mod/map trees (mod.json + cannon/base.obj +
        //     cannon/color.png) keep their nested layout so JSON paths
        //     like "cannon/base.cmesh" resolve at runtime.
        //
        // Crafter.Asset must be reachable through cfg.dependencies (the
        // build engine links its library API into crafter-build via a
        // self-host pass). Forwarded to a consuming executable's bin dir
        // alongside .spv shaders and cfg.files entries.
        std::vector<fs::path> assets;
        std::vector<ExternalDependency> externalDependencies;
        std::vector<std::string> compileFlags;
        std::vector<std::string> linkFlags;
        // Browser-wasm feature-detected variants. Empty (the default) builds a
        // single outputName.wasm with the baseline wasm flag set. Non-empty
        // builds the baseline plus one outputName.<label>.wasm per entry, each
        // recompiling the whole build graph with that entry's `flags`;
        // EnableWasiBrowserRuntime emits a variants.json manifest the shipped
        // runtime.js uses to pick the right variant per browser. Populate via
        // EnableWasiRelaxedSimdVariant for the common case.
        std::vector<WasmVariant> wasmVariants;
        // Extra wasm codegen flags injected into this configuration's compile +
        // link command for the active variant pass. Set across the whole build
        // graph by the variant driver inside Build(); part of VariantId so each
        // variant's objects/PCMs land in their own build+bin dir and never
        // clobber the baseline's. Not for direct project use — declare
        // wasmVariants instead.
        std::vector<std::string> wasmVariantFlags;
        std::vector<Test> tests;
        CRAFTER_API void GetInterfacesAndImplementations(std::span<fs::path> interfaces, std::span<fs::path> implementations);
        // Declare a test. Sources default to `tests/<name>/main.cpp` resolved
        // against this Configuration's path; target/march/mtune/debug are
        // inherited from this Configuration so cross-arch projects don't have
        // to re-specify. Returns a builder for chaining defines, deps, etc.
        // Defined in Crafter.Build:Test.
        CRAFTER_API struct TestBuilder AddTest(std::string_view name);
        // Same as AddTest, but compiles the parent's `interfaces` directly
        // into this test's Configuration (rather than going through a dep).
        // Use when the test must rebuild those interfaces with its own
        // compile flags — typically per-march SIMD codegen.
        CRAFTER_API struct TestBuilder AddTest(std::string_view name, std::span<fs::path> interfaces);
        // Math-style fan-out: one Test per MarchTier, all sharing the same
        // `tests/<name>/main.cpp` source and the same interface set, each
        // compiled with the tier's `-march`/`-mtune`. Test names are
        // `<name>-<march>`.
        CRAFTER_API void AddMarchVariants(std::string_view name,
                                          std::span<fs::path> interfaces,
                                          std::span<const struct MarchTier> tiers);
        // Suffix that uniquely identifies this Configuration's compile state.
        // target+march+mtune are spelled out for readability; the rest
        // (type, debug, sysroot, defines, compileFlags) collapse into a short
        // hash so two Configurations sharing a path but with different
        // compile state can't clobber each other's outputs.
        std::string VariantId() const {
            std::string compileKey;
            compileKey += std::to_string(static_cast<int>(type));
            compileKey += '|';
            compileKey += debug ? '1' : '0';
            compileKey += '|';
            compileKey += sysroot;
            for (const Define& d : defines) {
                compileKey += "|D:";
                compileKey += d.name;
                compileKey += '=';
                compileKey += d.value;
            }
            for (const std::string& f : compileFlags) {
                compileKey += "|F:";
                compileKey += f;
            }
            // Wasm variant codegen flags perturb every object/PCM, so they must
            // key into a distinct build+bin dir from the baseline (and from
            // each other) to avoid clobbering.
            for (const std::string& f : wasmVariantFlags) {
                compileKey += "|W:";
                compileKey += f;
            }
            std::size_t configHash = std::hash<std::string>{}(compileKey);
            return std::format("{}-{}-{}-{}-{:08x}", name, target, march, mtune, configHash);
        }
        fs::path BuildDir() const { return path / "build" / VariantId(); }
        fs::path BinDir() const { return path / "bin" / VariantId(); }
        fs::path PcmDir() const {
            return type == ConfigurationType::Executable ? BuildDir() : BinDir();
        }
    };

    struct Test {
        Configuration config;
        TestRunner runner;
        std::chrono::seconds timeout{60};
        std::vector<std::string> args;
        // Declarative preconditions. Each entry is "tool:<name>",
        // "file:<path>", or "env:<VAR>". Evaluated before the test runs; any
        // unmet require turns the test into a Skip with a derived reason.
        // Also doubles as the "I know this runner might not be here" opt-in:
        // when the test's derived runner needs a tool (e.g. qemu-aarch64,
        // wasmtime, wine) and the matching tool: entry isn't present, an
        // unavailable runner becomes a Fail instead of a silent Skip — the
        // dependency has to be declared to be allowed to be missing.
        std::vector<std::string> requires_;
    };

    CRAFTER_API BuildResult Build(Configuration& config, std::unordered_map<fs::path, std::shared_future<BuildResult>>& depResults, std::mutex& depMutex);

    CRAFTER_API int Run(int argc, char** argv);

    // Add a small index.html + runtime.js pair next to the .wasm output so the
    // build can be loaded directly in a browser (just `serve` the bin dir and
    // open it). Opt-in: WASI builds destined for wasmtime/wasmer don't need
    // this and shouldn't carry the extra files. Call from project.cpp after
    // outputName is set; index.html is generated against the current
    // outputName so renaming the binary later requires another call.
    CRAFTER_API void EnableWasiBrowserRuntime(Configuration& cfg);

    // Register the relaxed-SIMD codegen variant on cfg. Builds an additional
    // outputName.relaxed-simd.wasm compiled with -mrelaxed-simd (FMA,
    // dot-product, relaxed swizzle/laneselect, …); the shipped runtime serves
    // it only to engines that report relaxed-SIMD support (Chrome 114+, Firefox
    // 120+) and falls back to the baseline outputName.wasm everywhere else
    // (e.g. Safari, which still gates relaxed SIMD behind a flag as of mid
    // 2026). Idempotent. Call before EnableWasiBrowserRuntime so the emitted
    // variants.json manifest includes it. A no-op for non-wasm targets at build
    // time (no wasm is produced), but harmless to declare unconditionally.
    CRAFTER_API void EnableWasiRelaxedSimdVariant(Configuration& cfg);

    // View over the project's args with simple query helpers. Has(flag) for
    // boolean switches; Get(prefix) for valued options (e.g. Get("--prefix=")
    // returns the substring after the equals). Definitions are out-of-line
    // and CRAFTER_API so they cross the Windows DLL boundary cleanly — clang
    // does not emit module-attached in-class inline bodies into consumers.
    struct ArgQuery {
        std::span<const std::string_view> args;
        CRAFTER_API bool Has(std::string_view flag) const;
        CRAFTER_API std::optional<std::string> Get(std::string_view prefix) const;
    };

    // Apply the framework's standard CLI args + env vars onto cfg:
    //   --debug             cfg.debug = true
    //   --target=<triple>   cfg.target = <triple>
    //   --march=<value>     cfg.march = <value>
    //   --mtune=<value>     cfg.mtune = <value>
    //   --lib               cfg.type promoted Executable → LibraryStatic
    //   --shared            cfg.type promoted LibraryStatic → LibraryDynamic
    // Promotions chain in priority order so `--lib --shared` lands on
    // LibraryDynamic regardless of arg order; each is a no-op when the
    // baseline doesn't match (e.g. --shared on an Executable, or --lib on a
    // pre-set library).
    //   $CRAFTER_BUILD_MARCH / $CRAFTER_BUILD_MTUNE seed march/mtune.
    // Env applies first, then args, so CLI wins over env wins over caller's
    // pre-set defaults. Returns an ArgQuery over the same span so projects
    // can query their own flags (`--timing`, ...) without re-rolling the
    // for-arg-in-args loop.
    CRAFTER_API ArgQuery ApplyStandardArgs(Configuration& cfg, std::span<const std::string_view> args);
}