// Small self-contained checks for the pieces that have no GUI dependency.

#include <atomic>
#include <cstdio>
#include <cstdlib>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <mutex>
#include <string>
#include <vector>

#include "core/chain.hpp"
#include "core/project.hpp"
#include "core/registry.hpp"
#include "core/rng.hpp"
#include "effects/blur.hpp"
#include "effects/scanlines.hpp"

namespace {

int failures = 0;

void check(bool condition, const std::string& what) {
    if (condition) {
        std::cout << "  ok   " << what << "\n";
    } else {
        std::cout << "  FAIL " << what << "\n";
        ++failures;
    }
}

effector::Image gradient(int width, int height, int shade) {
    effector::Image image(width, height);
    for (int y = 0; y < height; ++y) {
        auto* row = image.row(y);
        for (int x = 0; x < width; ++x) {
            row[x * 3 + 0] = static_cast<std::uint8_t>((x + shade) & 0xFF);
            row[x * 3 + 1] = static_cast<std::uint8_t>((y + shade) & 0xFF);
            row[x * 3 + 2] = static_cast<std::uint8_t>(shade);
        }
    }
    return image;
}

bool sameBytes(const effector::Image& a, const effector::Image& b) {
    if (a.width() != b.width() || a.height() != b.height()) return false;
    return std::equal(a.data(), a.data() + a.byteSize(), b.data());
}

// Alternating black and white columns: any blur along x has to pull these
// towards mid grey.
effector::Image stripes(int width, int height) {
    effector::Image image(width, height);
    for (int y = 0; y < height; ++y) {
        auto* row = image.row(y);
        for (int x = 0; x < width; ++x) {
            const std::uint8_t value = (x % 2 == 0) ? 0 : 255;
            row[x * 3 + 0] = row[x * 3 + 1] = row[x * 3 + 2] = value;
        }
    }
    return image;
}

effector::Image renderBlur(const std::vector<effector::Image>& sources, int width, int height,
                           std::uint64_t seed, const effector::ParamValues& values) {
    effector::BlurEffect effect;
    effector::Rng rng(seed);
    auto merged = effect.defaults();
    for (const auto& [key, value] : values) merged[key] = value;
    return effect.render(sources, width, height, rng, merged);
}

effector::Image render(const std::vector<effector::Image>& sources, int width, int height,
                       std::uint64_t seed, const effector::ParamValues& values) {
    effector::ScanlinesEffect effect;
    effector::Rng rng(seed);
    auto merged = effect.defaults();
    for (const auto& [key, value] : values) merged[key] = value;
    return effect.render(sources, width, height, rng, merged);
}

}  // namespace

int main() {
    using namespace effector;

    std::cout << "rng\n";
    {
        Rng a(42);
        Rng b(42);
        bool identical = true;
        for (int i = 0; i < 1000; ++i) identical = identical && a.next() == b.next();
        check(identical, "same seed yields the same stream");

        Rng c(7);
        bool inBounds = true;
        for (int i = 0; i < 10000; ++i) {
            const long value = c.inRange(-4, 9);
            inBounds = inBounds && value >= -4 && value <= 9;
        }
        check(inBounds, "inRange stays within bounds");
    }

    std::cout << "registry\n";
    {
        check(!effects().empty(), "registry is populated");
        check(effectByName("scanlines")->title() == "Scanlines", "lookup by name");
        bool threw = false;
        try {
            effectByName("nope");
        } catch (const EffectError&) {
            threw = true;
        }
        check(threw, "unknown effect throws");
    }

    std::cout << "scanlines\n";
    {
        std::vector<Image> sources = {gradient(1200, 800, 10), gradient(640, 480, 90),
                                      gradient(300, 200, 200)};

        const auto first = render(sources, 800, 600, 1, {{"strip_height", 6L}, {"jitter", 3L}});
        const auto again = render(sources, 800, 600, 1, {{"strip_height", 6L}, {"jitter", 3L}});
        const auto other = render(sources, 800, 600, 2, {{"strip_height", 6L}, {"jitter", 3L}});

        check(first.width() == 800 && first.height() == 600, "canvas has the requested size");
        check(sameBytes(first, again), "same seed reproduces the image");
        check(!sameBytes(first, other), "a different seed changes the image");

        const auto thin = render(sources, 400, 300, 7, {{"strip_height", 1L}});
        check(thin.width() == 400 && thin.height() == 300, "strip height of 1");

        // Canvas wider and taller than the only source: exercises tiling and the
        // clamp of the strip height to the source height.
        std::vector<Image> small = {gradient(300, 200, 5)};
        const auto tiled = render(small, 1000, 700, 9, {{"strip_height", 400L}, {"jitter", 50L}});
        check(tiled.width() == 1000 && tiled.height() == 700, "tiling a narrow source");
        bool tiles = true;
        for (int y = 0; y < tiled.height(); ++y) {
            const auto* row = tiled.row(y);
            for (int c = 0; c < 3; ++c) tiles = tiles && row[c] == row[300 * 3 + c];
        }
        check(tiles, "tiled columns repeat with the source width");

        const auto ordered = render(sources, 500, 500, 3, {{"strip_height", 20L}, {"keep_order", true}});
        check(ordered.height() == 500, "keep_order fills the canvas");

        bool threw = false;
        try {
            render({}, 100, 100, 1, {});
        } catch (const EffectError&) {
            threw = true;
        }
        check(threw, "no sources throws");
    }

    std::cout << "blur\n";
    {
        std::vector<Image> sources = {gradient(1200, 800, 10), gradient(640, 480, 90)};

        const auto first = renderBlur(sources, 400, 300, 4, {{"radius", 10L}});
        const auto again = renderBlur(sources, 400, 300, 4, {{"radius", 10L}});
        const auto other = renderBlur(sources, 400, 300, 11, {{"radius", 10L}});
        check(first.width() == 400 && first.height() == 300, "canvas has the requested size");
        check(sameBytes(first, again), "same seed reproduces the image");
        check(!sameBytes(first, other), "a different seed changes the image");

        // A wide blur over one-pixel stripes has to land near mid grey, and only
        // along the axis it is applied to.
        std::vector<Image> striped = {stripes(200, 100)};
        const auto flattened = renderBlur(striped, 200, 100, 1,
                                          {{"radius", 8L}, {"direction", std::string("horizontal")}});
        // The clamped edges ramp in over radius * passes pixels on each side.
        bool grey = true;
        for (int x = 32; x < 168; ++x) grey = grey && std::abs(flattened.row(50)[x * 3] - 127) <= 2;
        check(grey, "a horizontal blur evens out vertical stripes");

        const auto untouched = renderBlur(striped, 200, 100, 1,
                                          {{"radius", 8L}, {"direction", std::string("vertical")}});
        check(untouched.row(50)[0] == 0 && untouched.row(50)[3] == 255,
              "a vertical blur leaves columns alone");

        // Every column is uniform, so a vertical blur must not change anything.
        const auto vertical = renderBlur(striped, 200, 100, 1,
                                         {{"radius", 4L}, {"passes", 3L}, {"direction", std::string("vertical")}});
        check(sameBytes(untouched, vertical), "repeated vertical passes stay stable");

        // Radius larger than the canvas must clamp rather than read out of bounds.
        const auto tiny = renderBlur(striped, 3, 3, 2, {{"radius", 200L}});
        check(tiny.width() == 3 && tiny.height() == 3, "radius wider than the canvas is clamped");

        const auto pinned = renderBlur(sources, 300, 200, 6, {{"first_source", true}});
        const auto pinnedAgain = renderBlur(sources, 300, 200, 6, {{"first_source", true}});
        check(sameBytes(pinned, pinnedAgain), "first_source is reproducible");

        // Blur declares that it needs no sources, so with none it softens the
        // empty canvas it starts from instead of refusing to run.
        const auto blank = renderBlur({}, 100, 100, 1, {});
        bool allBlack = blank.width() == 100 && blank.height() == 100;
        for (std::size_t i = 0; i < blank.byteSize(); ++i) allBlack = allBlack && blank.data()[i] == 0;
        check(allBlack, "without sources blur renders an empty canvas");
    }

    std::cout << "chain\n";
    {
        std::vector<Image> sources = {gradient(1200, 800, 10), gradient(640, 480, 90)};

        ChainStage scanlines{effectByName("scanlines"), {{"strip_height", 6L}}};
        ChainStage blur{effectByName("blur"), {{"radius", 6L}}};

        Rng single(5);
        const auto direct = renderChain({scanlines}, sources, 400, 300, single);
        const auto alone = render(sources, 400, 300, 5, {{"strip_height", 6L}});
        check(sameBytes(direct, alone), "a one stage chain matches the effect on its own");

        Rng a(5);
        Rng b(5);
        const auto cascaded = renderChain({scanlines, blur}, sources, 400, 300, a);
        const auto again = renderChain({scanlines, blur}, sources, 400, 300, b);
        check(cascaded.width() == 400 && cascaded.height() == 300, "the chain keeps the canvas size");
        check(sameBytes(cascaded, again), "the same seed reproduces the cascade");
        check(!sameBytes(cascaded, direct), "a second stage changes the image");

        // Order matters: blurring scanlines is not the same as scanning a blur.
        Rng forward(5);
        Rng backward(5);
        const auto blurLast = renderChain({scanlines, blur}, sources, 400, 300, forward);
        const auto blurFirst = renderChain({blur, scanlines}, sources, 400, 300, backward);
        check(!sameBytes(blurLast, blurFirst), "the stage order changes the image");

        check(chainTitle({scanlines, blur}) == "Scanlines \u2192 Blur", "the chain has a readable title");
        check(chainSlug({scanlines, blur}) == "scanlines-blur", "the chain has a file name slug");

        bool threw = false;
        try {
            Rng rng(1);
            renderChain({}, sources, 100, 100, rng);
        } catch (const EffectError&) {
            threw = true;
        }
        check(threw, "an empty chain throws");

        // Sources are an effect's own business: scanlines cuts strips out of
        // them, blur only softens what it is handed and runs without any.
        check(effectByName("scanlines")->needsSources(), "scanlines needs source images");
        check(!effectByName("blur")->needsSources(), "blur needs no source images");
        check(chainNeedsSources({scanlines, blur}), "a chain led by scanlines needs sources");
        check(!chainNeedsSources({blur, scanlines}),
              "a chain led by blur needs none, later stages see the stage before them");
        check(!chainNeedsSources({}), "an empty chain needs no sources");

        Rng bare(5);
        const auto sourceless = renderChain({blur}, {}, 200, 150, bare);
        check(sourceless.width() == 200 && sourceless.height() == 150,
              "blur renders a canvas without sources");

        bool scanlinesThrew = false;
        try {
            Rng rng(1);
            renderChain({scanlines}, {}, 100, 100, rng);
        } catch (const EffectError&) {
            scanlinesThrew = true;
        }
        check(scanlinesThrew, "scanlines still refuses to run without sources");
    }

    std::cout << "project\n";
    {
        const auto dir = std::filesystem::temp_directory_path() / "effector_test_project";
        std::filesystem::create_directories(dir);
        const auto source = dir / "source.png";
        gradient(64, 48, 7).save(source.string());

        Project project;
        project.sources = {source.string(), "/elsewhere/other.png"};
        project.stages.push_back({effectByName("scanlines"), {{"strip_height", 9L}}});
        project.stages.push_back(
            {effectByName("blur"), {{"radius", 3L}, {"direction", std::string("vertical")}}});
        project.width = 640;
        project.height = 400;
        project.seed = 1234567890123ULL;

        const auto file = dir / "test.json";
        saveProject(file.string(), project);
        const auto reloaded = loadProject(file.string());

        check(reloaded.width == 640 && reloaded.height == 400, "the canvas survives a round trip");
        check(reloaded.seed && *reloaded.seed == 1234567890123ULL, "the seed survives a round trip");
        check(reloaded.stages.size() == 2 && reloaded.stages[0].effect->name() == "scanlines" &&
                  reloaded.stages[1].effect->name() == "blur",
              "the chain keeps its effects and their order");
        check(paramInt(reloaded.stages[0].values, "strip_height", 0) == 9 &&
                  paramInt(reloaded.stages[1].values, "radius", 0) == 3 &&
                  paramChoice(reloaded.stages[1].values, "direction", "") == "vertical",
              "the stage params survive a round trip");
        check(paramInt(reloaded.stages[0].values, "jitter", -1) ==
                  paramInt(effectByName("scanlines")->defaults(), "jitter", -2),
              "params the file leaves out keep their default");

        // A source next to the project is written relative, so the folder can
        // be moved; anything outside it stays absolute.
        std::ifstream stream(file.string(), std::ios::binary);
        const std::string text((std::istreambuf_iterator<char>(stream)),
                               std::istreambuf_iterator<char>());
        check(text.find("\"source.png\"") != std::string::npos, "a nearby source is written relative");
        check(text.find("\"/elsewhere/other.png\"") != std::string::npos,
              "a source elsewhere stays absolute");
        check(reloaded.sources.size() == 2 && reloaded.sources[0] == source.string(),
              "a relative source is resolved against the project");

        // The point of a project: the same picture comes back out of the file.
        std::vector<Image> sources = {gradient(300, 200, 4)};
        Rng before(*project.seed);
        Rng after(*reloaded.seed);
        const auto original = renderChain(project.stages, sources, project.width, project.height, before);
        const auto restored =
            renderChain(reloaded.stages, sources, reloaded.width, reloaded.height, after);
        check(sameBytes(original, restored), "a reloaded project renders the same image");

        // Params the effects do not declare are dropped rather than carried.
        const auto stripped = projectFromJson(projectToJson(reloaded));
        check(stripped.stages[0].values.find("radius") == stripped.stages[0].values.end(),
              "a stage only keeps the params its effect declares");

        int refusals = 0;
        for (const char* bad : {"{\"chain\": [{\"effect\": \"nope\"}]}", "{\"chain\": []}",
                                "{\"chain\": [{\"effect\": \"blur\"},]}", "not json at all"}) {
            try {
                projectFromJson(bad);
            } catch (const EffectError&) {
                ++refusals;
            }
        }
        check(refusals == 4, "a broken project is refused");

        bool threw = false;
        try {
            loadProject((dir / "missing.json").string());
        } catch (const EffectError&) {
            threw = true;
        }
        check(threw, "a missing project file throws");

        std::filesystem::remove_all(dir);
    }

    std::cout << "image io\n";
    {
        const auto path = std::filesystem::temp_directory_path() / "effector_test_roundtrip.png";
        const auto original = gradient(64, 48, 3);
        original.save(path.string());
        const auto reloaded = Image::load(path.string());
        check(sameBytes(original, reloaded), "png round trip is lossless");
        std::filesystem::remove(path);

        bool threw = false;
        try {
            Image::load("/definitely/not/here.png");
        } catch (const std::exception&) {
            threw = true;
        }
        check(threw, "missing file throws");
    }

    std::cout << "batch loading\n";
    {
        const auto dir = std::filesystem::temp_directory_path() / "effector_test_batch";
        std::filesystem::create_directories(dir);
        std::vector<std::string> paths;
        for (int i = 0; i < 6; ++i) {
            const auto path = dir / ("src" + std::to_string(i) + ".png");
            gradient(32, 24, i + 1).save(path.string());
            paths.push_back(path.string());
        }
        paths.push_back((dir / "missing.png").string());

        std::atomic<std::size_t> calls{0};
        std::size_t lastTotal = 0;
        std::mutex mutex;
        LoadProgress progress;
        progress.onFile = [&](std::size_t done, std::size_t total, const std::string&) {
            std::lock_guard<std::mutex> lock(mutex);
            ++calls;
            lastTotal = total;
            check(done >= 1 && done <= total, "progress step is within the batch");
        };

        std::vector<LoadFailure> failuresOut;
        const auto images = loadImages(paths, failuresOut, &progress);
        check(images.size() == 6, "every readable image is returned");
        check(failuresOut.size() == 1, "the unreadable one is reported");
        check(calls.load() == paths.size(), "progress fires once per file");
        check(lastTotal == paths.size(), "progress reports the batch size");
        check(images.front().path() == paths.front(), "input order is preserved");

        std::atomic<bool> cancel{true};
        LoadProgress cancelled;
        cancelled.cancel = &cancel;
        std::vector<LoadFailure> ignored;
        const auto none = loadImages(paths, ignored, &cancelled);
        check(none.empty(), "a cancelled batch loads nothing");

        std::filesystem::remove_all(dir);
    }

    std::cout << (failures == 0 ? "\nall checks passed\n" : "\n" + std::to_string(failures) + " failed\n");
    return failures == 0 ? 0 : 1;
}