#include <dmf-engine/api_server.hpp>
#include <dmf-engine/graph.hpp>
#include <dmf-engine/flow_manager.hpp>
#include <dmf-engine/process_manager.hpp>

#include <libwebsockets.h>

#include <nlohmann/json.hpp>

#include <spdlog/spdlog.h>

#include <cstring>
#include <string>

namespace dmf_engine {

struct ApiServerImpl {
    uint16_t port = 0;
    Graph* graph = nullptr;
    FlowManager* flow_manager = nullptr;
    ProcessManager* process_manager = nullptr;
    struct lws_context* context = nullptr;
};

struct ApiServer::Impl {
    std::unique_ptr<ApiServerImpl> data;
};

struct HttpRequest {
    std::string method;
    std::string path;
    std::string body;
    bool body_done = false;
};

static ApiServerImpl* g_impl = nullptr;

static int callback_http(struct lws* wsi, enum lws_callback_reasons reason,
                         void* user, void* in, size_t len) {
    auto* req = static_cast<HttpRequest*>(user);

    switch (reason) {
    case LWS_CALLBACK_HTTP: {
        new (req) HttpRequest();

        if (lws_hdr_total_length(wsi, WSI_TOKEN_POST_URI) > 0) {
            req->method = "POST";
            char buf[256] = {};
            lws_hdr_copy(wsi, buf, sizeof(buf), WSI_TOKEN_POST_URI);
            req->path = buf;
        } else {
            req->method = "GET";
            char buf[256] = {};
            lws_hdr_copy(wsi, buf, sizeof(buf), WSI_TOKEN_GET_URI);
            req->path = buf;
        }
        break;
    }
    case LWS_CALLBACK_HTTP_BODY: {
        req->body.append(static_cast<char*>(in), len);
        break;
    }
    case LWS_CALLBACK_HTTP_BODY_COMPLETION: {
        if (!g_impl || !g_impl->graph) {
            lws_return_http_status(wsi, HTTP_STATUS_INTERNAL_SERVER_ERROR, "Server error");
            return -1;
        }

        std::string status_str, content_type, response_body;

        auto ok = [&](const nlohmann::json& j) {
            status_str = "200 OK";
            response_body = j.dump();
        };
        auto created = [&](const nlohmann::json& j) {
            status_str = "201 Created";
            response_body = j.dump();
        };
        auto error_resp = [&](int code, const std::string& msg) {
            status_str = std::to_string(code) + " Error";
            response_body = nlohmann::json({{"error", msg}}).dump();
        };

        content_type = "application/json";

        try {
            nlohmann::json req_body = req->body.empty() ? nlohmann::json::object() : nlohmann::json::parse(req->body);

            auto& graph = *g_impl->graph;
            auto& fm = *g_impl->flow_manager;
            auto& pm = *g_impl->process_manager;

            if (req->path == "/api/graph" && req->method == "GET") {
                ok(graph.serialize());
            } else if (req->path == "/api/graph/nodes" && req->method == "POST") {
                if (!req_body.contains("type")) {
                    error_resp(400, "Missing 'type' field");
                } else {
                    auto type = req_body["type"].get<std::string>();
                    auto config = req_body.value("config", nlohmann::json::object());
                    auto id = graph.add_node(type, config);
                    created({{"id", id}});
                }
            } else if (req->path.find("/api/graph/nodes/") == 0 && req->method == "DELETE") {
                auto node_id = req->path.substr(std::string("/api/graph/nodes/").length());
                if (graph.remove_node(node_id)) {
                    ok({{"deleted", node_id}});
                } else {
                    error_resp(404, "Node not found: " + node_id);
                }
            } else if (req->path == "/api/graph/edges" && req->method == "POST") {
                if (!req_body.contains("from_node") || !req_body.contains("to_node")) {
                    error_resp(400, "Missing from_node/to_node");
                } else {
                    auto from_node = req_body["from_node"].get<std::string>();
                    auto from_port = req_body.value("from_port", "video_out");
                    auto to_node = req_body["to_node"].get<std::string>();
                    auto to_port = req_body.value("to_port", "video_in");

                    auto flow_id = fm.create_flow_id();
                    auto flow_def = fm.create_v210_flow_def(flow_id, 1920, 1080, 50, 1);

                    auto edge_id = graph.add_edge(from_node, from_port, to_node, to_port, flow_id, flow_def);
                    created({{"id", edge_id}, {"flow_id", flow_id}});
                }
            } else if (req->path.find("/api/graph/edges/") == 0 && req->method == "DELETE") {
                auto edge_id = req->path.substr(std::string("/api/graph/edges/").length());
                if (graph.remove_edge(edge_id)) {
                    ok({{"deleted", edge_id}});
                } else {
                    error_resp(404, "Edge not found: " + edge_id);
                }
            } else if (req->path == "/api/graph/start" && req->method == "POST") {
                auto nodes = graph.get_nodes();
                uint16_t port = 9100;
                for (auto& node : nodes) {
                    pm.start_node(const_cast<GraphNode&>(node), "/dev/shm/mxl", port++);
                }
                ok({{"status", "started"}});
            } else if (req->path == "/api/graph/stop" && req->method == "POST") {
                auto nodes = graph.get_nodes();
                for (auto& node : nodes) {
                    pm.stop_node(const_cast<GraphNode&>(node));
                }
                ok({{"status", "stopped"}});
            } else {
                error_resp(404, "Not found: " + req->method + " " + req->path);
            }
        } catch (const nlohmann::json::exception& e) {
            error_resp(400, std::string("JSON error: ") + e.what());
        } catch (const std::exception& e) {
            error_resp(500, e.what());
        }

        auto headers = "HTTP/1.1 " + status_str + "\r\n"
                       "Content-Type: " + content_type + "\r\n"
                       "Access-Control-Allow-Origin: *\r\n"
                       "Access-Control-Allow-Methods: GET, POST, DELETE, PUT, OPTIONS\r\n"
                       "Access-Control-Allow-Headers: Content-Type\r\n"
                       "Content-Length: " + std::to_string(response_body.size()) + "\r\n"
                       "\r\n";

        std::vector<uint8_t> buf(LWS_PRE + headers.size() + response_body.size());
        std::memcpy(buf.data() + LWS_PRE, headers.data(), headers.size());
        std::memcpy(buf.data() + LWS_PRE + headers.size(), response_body.data(), response_body.size());

        lws_write(wsi, buf.data() + LWS_PRE, headers.size() + response_body.size(), LWS_WRITE_HTTP);

        if (lws_http_transaction_completed(wsi)) {
            return -1;
        }
        return 0;
    }
    default:
        break;
    }
    return 0;
}

static const struct lws_protocols protocols[] = {
    {"http-api", callback_http, sizeof(HttpRequest), 0},
    {nullptr, nullptr, 0, 0},
};

ApiServer::ApiServer(uint16_t port, Graph& graph, FlowManager& flow_manager, ProcessManager& process_manager)
    : impl_(std::make_unique<Impl>()) {
    impl_->data = std::make_unique<ApiServerImpl>();
    impl_->data->port = port;
    impl_->data->graph = &graph;
    impl_->data->flow_manager = &flow_manager;
    impl_->data->process_manager = &process_manager;

    g_impl = impl_->data.get();

    struct lws_context_creation_info info;
    std::memset(&info, 0, sizeof(info));
    info.port = port;
    info.protocols = protocols;
    info.gid = -1;
    info.uid = -1;

    impl_->data->context = lws_create_context(&info);
    if (!impl_->data->context) {
        spdlog::error("Failed to create HTTP context on port {}", port);
        throw std::runtime_error("Failed to create HTTP context");
    }
    spdlog::info("API server: listening on port {}", port);
}

ApiServer::~ApiServer() {
    if (impl_->data && impl_->data->context) {
        lws_context_destroy(impl_->data->context);
    }
    if (g_impl == impl_->data.get()) {
        g_impl = nullptr;
    }
}

void ApiServer::poll(int timeout_ms) {
    lws_service(impl_->data->context, timeout_ms);
}

} // namespace dmf_engine