#include "server.hpp"
#include "errors.hpp"
#include "json_http.hpp"
#include <chrono>
#include <fstream>
#include <sstream>

namespace svapi {

ApiServer::ApiServer(ServerDeps deps) : d_(std::move(deps)) {}

static bool keyExpired(const ApiKey& k) {
    if (!k.scope) return false;
    auto now = (uint64_t)std::chrono::duration_cast<std::chrono::seconds>(
        std::chrono::system_clock::now().time_since_epoch()).count();
    return k.scope->expired(now);
}

std::optional<ApiKey> resolveKey(ServerDeps& d, const httplib::Request& req) {
    if (auto it = req.headers.find("Authorization"); it != req.headers.end())
        if (auto tok = bearerToken(it->second))
            if (auto k = d.keys.lookup(*tok)) { if (!keyExpired(*k)) return k; return std::nullopt; }
    if (auto it = req.headers.find("Cookie"); it != req.headers.end())
        if (auto c = cookieValue(it->second, "svapi_session"))
            if (auto keyVal = d.sessions.keyFor(*c, std::chrono::system_clock::now()))
                if (auto k = d.keys.lookup(*keyVal)) { if (!keyExpired(*k)) return k; return std::nullopt; }
    return std::nullopt;
}
ApiKey requireKey(ServerDeps& d, const httplib::Request& req) {
    if (auto k = resolveKey(d, req)) return *k;
    throw ApiError(ErrCode::Unauthorized, "unauthorized", "missing or invalid credentials");
}
void requireAdmin(const ApiKey& k) {
    if (!k.admin) throw ApiError(ErrCode::Forbidden, "forbidden", "admin privilege required");
}
void requireProjectAccess(const ApiKey& k, const std::string& project) {
    if (!k.canAccess(project))
        throw ApiError(ErrCode::Forbidden, "forbidden", "key not granted project '" + project + "'");
}

void ApiServer::registerRoutes() {
    svr_.set_exception_handler([](const httplib::Request&, httplib::Response& res, std::exception_ptr ep) {
        try { std::rethrow_exception(ep); }
        catch (const ApiError& e) { sendJson(res, httpStatus(e.code), errorBody(e.slug, e.what())); }
        catch (const std::exception& e) { sendJson(res, 500, errorBody("internal", e.what())); }
    });

    // SPA history fallback: a hard navigation / refresh / direct URL to a client-side
    // route (e.g. /login, /settings) reaches the server as a 404 (no such static file).
    // Serve index.html so React Router can handle it. Excludes API/meta routes and asset
    // requests (paths with a file extension), which should keep their real 404.
    svr_.set_error_handler([this](const httplib::Request& req, httplib::Response& res) {
        if (res.status == 404 && req.method == "GET" && !d_.webuiDir.empty()
            && req.path.rfind("/api/", 0) != 0
            && req.path.rfind("/ui/", 0) != 0
            && req.path.rfind("/docs", 0) != 0
            && req.path != "/openapi.json" && req.path != "/llms.txt"
            && req.path != "/healthz" && req.path != "/readyz"
            && req.path.find('.') == std::string::npos) {
            std::ifstream f(d_.webuiDir + "/index.html", std::ios::binary);
            if (f) {
                std::stringstream ss; ss << f.rdbuf();
                res.set_content(ss.str(), "text/html");
                res.status = 200;
                return httplib::Server::HandlerResponse::Handled;
            }
        }
        return httplib::Server::HandlerResponse::Unhandled;
    });

    // Authenticate /api/* (authorization is per-handler).
    svr_.set_pre_routing_handler([this](const httplib::Request& req, httplib::Response& res) {
        if (req.method != "OPTIONS" && req.path.rfind("/api/", 0) == 0) {
            if (!resolveKey(d_, req)) {
                sendJson(res, 401, errorBody("unauthorized", "missing or invalid credentials"));
                return httplib::Server::HandlerResponse::Handled;
            }
        }
        return httplib::Server::HandlerResponse::Unhandled;
    });

    svr_.set_post_routing_handler([this](const httplib::Request& req, httplib::Response& res) {
        auto snap = d_.settings.snapshot();
        std::string responseOrigin;
        if (!snap->corsOrigins.empty() && snap->corsOrigins[0] == "*") {
            responseOrigin = "*";
        } else if (auto it = req.headers.find("Origin"); it != req.headers.end()) {
            for (const auto& a : snap->corsOrigins) if (a == it->second) { responseOrigin = it->second; break; }
        }
        if (!responseOrigin.empty()) {
            res.set_header("Access-Control-Allow-Origin", responseOrigin);
            if (responseOrigin != "*") res.set_header("Vary", "Origin");
        }
        res.set_header("Access-Control-Allow-Headers", "Authorization, Content-Type");
        res.set_header("Access-Control-Allow-Methods", "GET, POST, PUT, PATCH, DELETE, OPTIONS");
    });
    svr_.Options(R"(.*)", [](const httplib::Request&, httplib::Response& res) { res.status = 204; });

    registerMetaRoutes(*this);
    registerWebuiAuthRoutes(*this);
    registerProjectRoutes(*this);
    registerKeyRoutes(*this);
    registerCollectionRoutes(*this);
    registerDocumentRoutes(*this);
    registerVectorRoutes(*this);
    registerStatsRoutes(*this);
    registerSettingsRoutes(*this);

    if (!d_.shareDir.empty()) svr_.set_mount_point("/docs", d_.shareDir + "/docs");
    if (!d_.webuiDir.empty()) svr_.set_mount_point("/", d_.webuiDir);
}

int  ApiServer::bindToAnyPort(const std::string& host) { return svr_.bind_to_any_port(host); }
void ApiServer::listenAfterBind() { svr_.listen_after_bind(); }
bool ApiServer::listen(const std::string& host, uint16_t port) { return svr_.listen(host, port); }
void ApiServer::stop() { svr_.stop(); }

} // namespace svapi