#include "fgc/CompositeCameraSource.h"

#include <doctest/doctest.h>

#include <stdexcept>
#include <vector>

using namespace fgc;

namespace {

// A source of `count` cameras whose trigger() delivers one frame per camera,
// stamped `ts`, when `ready` - and reports nothing otherwise.
struct FakeSource : ICameraSource {
    int           count;
    long long     ts;
    bool          ready = true;
    bool          throws_on_open = false;
    int           triggers = 0;
    bool          started = false;
    std::string   why_offline;
    FrameCallback cb;

    FakeSource(int n, long long t) : count(n), ts(t) {}

    void open() override {
        if (throws_on_open) throw std::runtime_error("no camera");
    }
    void close() override {}
    void start() override { started = true; }
    void stop() override { started = false; }
    bool trigger() override {
        ++triggers;
        if (!ready) return false;
        for (int i = 0; i < count; ++i) {
            Frame f;
            f.cam_id       = i;
            f.timestamp_ms = ts + i;
            cb(f);
        }
        return true;
    }
    void setFrameCallback(FrameCallback c) override { cb = std::move(c); }
    int  cameraCount() const override { return count; }
    bool readFeature(int i, const std::string& name, double& v) override {
        v = i * 100 + ts;
        return name == "X";
    }
    std::string offline(int) override { return why_offline; }
    std::vector<CameraDeviceInfo> deviceInfo() override {
        std::vector<CameraDeviceInfo> out(count);
        for (int i = 0; i < count; ++i) out[i].id = std::to_string(ts) + ":" + std::to_string(i);
        return out;
    }
    bool grabFrame(int i, Frame& out, int) override {
        out              = Frame{};
        out.cam_id       = i;
        out.timestamp_ms = ts + 50;
        return true;
    }
};

struct Rig {
    FakeSource*            colour  = nullptr;
    FakeSource*            thermal = nullptr;
    std::unique_ptr<CompositeCameraSource> src;
    std::vector<Frame>     frames;

    explicit Rig(int colour_count = 1) {
        auto c  = std::make_unique<FakeSource>(colour_count, 1000);
        auto t  = std::make_unique<FakeSource>(1, 5000);
        colour  = c.get();
        thermal = t.get();
        std::vector<std::unique_ptr<ICameraSource>> v;
        v.push_back(std::move(c));
        v.push_back(std::move(t));
        src = std::make_unique<CompositeCameraSource>(std::move(v));
        src->setFrameCallback([this](const Frame& f) { frames.push_back(f); });
    }
};

}  // namespace

TEST_CASE("the composite numbers the cameras leader first, and counts them all") {
    Rig r(2);
    CHECK(r.src->cameraCount() == 3);
    REQUIRE(r.src->trigger());
    REQUIRE(r.frames.size() == 3);
    CHECK(r.frames[0].cam_id == 0);
    CHECK(r.frames[1].cam_id == 1);
    CHECK(r.frames[2].cam_id == 2);   // the thermal camera
}

TEST_CASE("one trigger gives every frame the leader's time") {
    Rig r;
    REQUIRE(r.src->trigger());
    REQUIRE(r.frames.size() == 2);
    CHECK(r.frames[0].timestamp_ms == 1000);
    CHECK(r.frames[1].timestamp_ms == 1000);   // not its own 5000
}

TEST_CASE("the followers are asked only once the leader has delivered") {
    Rig r;
    r.colour->ready = false;
    CHECK_FALSE(r.src->trigger());
    CHECK_FALSE(r.src->trigger());
    CHECK(r.thermal->triggers == 0);   // no thermal picture without its colour one
    CHECK(r.frames.empty());
    r.colour->ready = true;
    CHECK(r.src->trigger());
    CHECK(r.thermal->triggers == 1);
}

TEST_CASE("a follower with nothing to give costs only its own picture") {
    Rig r;
    r.thermal->ready = false;
    CHECK(r.src->trigger());
    REQUIRE(r.frames.size() == 1);
    CHECK(r.frames[0].cam_id == 0);
}

TEST_CASE("calls about one camera reach the source that has it") {
    Rig r(2);
    double v = 0;
    REQUIRE(r.src->readFeature(1, "X", v));
    CHECK(v == 1100);                 // colour source, its camera 1
    REQUIRE(r.src->readFeature(2, "X", v));
    CHECK(v == 5000);                 // thermal source, its camera 0
    CHECK_FALSE(r.src->readFeature(3, "X", v));

    r.thermal->why_offline = "unplugged";
    CHECK(r.src->offline(0).empty());
    CHECK(r.src->offline(2) == "unplugged");

    const auto d = r.src->deviceInfo();
    REQUIRE(d.size() == 3);
    CHECK(d[2].id == "5000:0");

    // A grab outside a trigger keeps its own time, under the global index.
    Frame f;
    REQUIRE(r.src->grabFrame(2, f, 10));
    CHECK(f.cam_id == 2);
    CHECK(f.timestamp_ms == 5050);
}

TEST_CASE("start and stop reach every source") {
    Rig r;
    r.src->start();
    CHECK(r.colour->started);
    CHECK(r.thermal->started);
    r.src->stop();
    CHECK_FALSE(r.thermal->started);
}

TEST_CASE("a follower that will not open does not stop the run; the leader does") {
    {
        Rig r;
        r.thermal->throws_on_open = true;
        CHECK_NOTHROW(r.src->open());
    }
    {
        Rig r;
        r.colour->throws_on_open = true;
        CHECK_THROWS(r.src->open());
    }
}