#include "service.h"
#include "capture/capture.h"
#include "common/json.h"
#include "common/log.h"
#include "config.h"
#include "engine.h"
#include "sinks/sink.h"

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define STATUS_SUBSCRIPTION_KEY "status"

struct service {
    LSHandle* handle;
    GMainLoop* loop;
    config_t* config;
    engine_t* engine;

    // Set from the engine thread, cleared by the idle handler on the main
    // loop. Coalesces a burst of updates into a single subscription push.
    gint status_pending;
};

// ---------------------------------------------------------------------------
// Reply helpers
// ---------------------------------------------------------------------------

static void reply_json(LSHandle* sh, LSMessage* msg, char* payload)
{
    if (!payload)
        return;
    LSError lserror;
    LSErrorInit(&lserror);
    if (!LSMessageReply(sh, msg, payload, &lserror)) {
        ERR("Luna reply failed: %s", lserror.message);
        LSErrorFree(&lserror);
    }
    free(payload);
}

static void reply_error(LSHandle* sh, LSMessage* msg, const char* fmt, ...)
    __attribute__((format(printf, 3, 4)));

static void reply_error(LSHandle* sh, LSMessage* msg, const char* fmt, ...)
{
    char text[320];
    va_list ap;
    va_start(ap, fmt);
    vsnprintf(text, sizeof(text), fmt, ap);
    va_end(ap);

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", false);
    jw_str(&w, "errorText", text);
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
}

static void reply_ok(LSHandle* sh, LSMessage* msg)
{
    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
}

// Parses the incoming payload. Returns NULL for an empty or malformed body,
// which every handler treats as "no arguments".
static json_value_t* message_payload(LSMessage* msg)
{
    const char* text = LSMessageGetPayload(msg);
    if (!text || !*text)
        return NULL;
    return json_parse(text);
}

// ---------------------------------------------------------------------------
// Status
// ---------------------------------------------------------------------------

static char* build_status(service_t* s, bool subscribed)
{
    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    if (subscribed)
        jw_bool(&w, "subscribed", true);

    engine_write_status(s->engine, &w);

    jw_str(&w, "configPath", config_path(s->config));
    jw_bool(&w, "configPersistent", config_is_persistent(s->config));
    jw_obj_close(&w);
    return jw_take(&w);
}

static void push_status(service_t* s)
{
    char* payload = build_status(s, true);
    if (!payload)
        return;

    LSError lserror;
    LSErrorInit(&lserror);
    if (!LSSubscriptionReply(s->handle, STATUS_SUBSCRIPTION_KEY, payload, &lserror)) {
        // Not fatal: it usually just means nobody is listening any more.
        DBG("Status push failed: %s", lserror.message);
        LSErrorFree(&lserror);
    }
    free(payload);
}

static gboolean status_idle(gpointer user)
{
    service_t* s = user;
    g_atomic_int_set(&s->status_pending, 0);
    push_status(s);
    return G_SOURCE_REMOVE;
}

// Called on the engine thread; must not touch Luna directly.
static void on_engine_notify(void* user)
{
    service_t* s = user;
    if (g_atomic_int_compare_and_exchange(&s->status_pending, 0, 1))
        g_idle_add(status_idle, s);
}

// ---------------------------------------------------------------------------
// Methods
// ---------------------------------------------------------------------------

static bool method_start(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;

    // An optional settings patch can be sent with start, so the UI can hit
    // "apply and start" in one call.
    json_value_t* payload = message_payload(msg);
    if (payload && payload->type == JSON_OBJECT && payload->u.object.count > 0) {
        char err[256];
        config_apply(s->config, payload, err, sizeof(err));
    }
    json_free(payload);

    char err[256] = { 0 };
    if (!engine_start(s->engine, config_root(s->config), err, sizeof(err))) {
        reply_error(sh, msg, "%s", err);
        return true;
    }
    reply_json(sh, msg, build_status(s, false));
    return true;
}

static bool method_stop(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;
    engine_stop(s->engine);
    reply_json(sh, msg, build_status(s, false));
    return true;
}

static bool method_get_status(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;
    bool subscribed = false;

    if (LSMessageIsSubscription(msg)) {
        LSError lserror;
        LSErrorInit(&lserror);
        if (LSSubscriptionAdd(sh, STATUS_SUBSCRIPTION_KEY, msg, &lserror)) {
            subscribed = true;
        } else {
            WARN("Cannot add subscriber: %s", lserror.message);
            LSErrorFree(&lserror);
        }
    }

    reply_json(sh, msg, build_status(s, subscribed));
    return true;
}

// The autostart script calls this: the act of calling it is what launches the
// service, and the reply tells the caller what happened.
static bool method_is_running(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;
    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_bool(&w, "isRunning", engine_state(s->engine) == ENGINE_RUNNING);
    jw_str(&w, "state", engine_state_name(engine_state(s->engine)));
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
    return true;
}

static bool method_get_config(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_str(&w, "path", config_path(s->config));
    jw_bool(&w, "persistent", config_is_persistent(s->config));
    jw_value(&w, "settings", config_root(s->config));
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
    return true;
}

static bool method_set_config(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;

    json_value_t* payload = message_payload(msg);
    if (!payload || payload->type != JSON_OBJECT) {
        json_free(payload);
        reply_error(sh, msg, "expected an object of settings to change");
        return true;
    }

    // Accept either the settings directly or wrapped in "settings", so the
    // frontend can send whichever reads better at the call site.
    const json_value_t* patch = json_get(payload, "settings");
    if (!patch)
        patch = payload;

    char err[256] = { 0 };
    bool saved = config_apply(s->config, patch, err, sizeof(err));

    const char* level = json_str(config_root(s->config), "logLevel", "info");
    if (strcmp(level, "debug") == 0)
        log_set_level(LOG_DEBUG);
    else if (strcmp(level, "warn") == 0)
        log_set_level(LOG_WARN);
    else if (strcmp(level, "error") == 0)
        log_set_level(LOG_ERROR);
    else
        log_set_level(LOG_INFO);

    json_free(payload);

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_bool(&w, "saved", saved);
    if (!saved)
        jw_str(&w, "warning", err);
    // Changing settings while capturing does nothing until the next start;
    // say so rather than silently ignoring half of them.
    jw_bool(&w, "restartRequired", engine_is_active(s->engine));
    jw_value(&w, "settings", config_root(s->config));
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));

    on_engine_notify(s);
    return true;
}

static bool method_reset_config(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;

    json_value_t* defaults = config_defaults();
    if (!defaults) {
        reply_error(sh, msg, "cannot build default settings");
        return true;
    }

    char err[256] = { 0 };
    bool saved = config_apply(s->config, defaults, err, sizeof(err));
    json_free(defaults);

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_bool(&w, "saved", saved);
    jw_value(&w, "settings", config_root(s->config));
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
    return true;
}

static bool method_list_backends(LSHandle* sh, LSMessage* msg, void* ctx)
{
    (void)ctx;

    size_t count = 0;
    const capture_driver_t* const* drivers = capture_drivers(&count);

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_arr_open(&w, "backends");
    for (size_t i = 0; i < count; i++) {
        jw_obj_open(&w, NULL);
        jw_str(&w, "id", drivers[i]->id);
        jw_str(&w, "name", drivers[i]->name);
        jw_str(&w, "description", drivers[i]->description);
        jw_bool(&w, "available", drivers[i]->available());
        jw_obj_close(&w);
    }
    jw_arr_close(&w);
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
    return true;
}

static bool method_list_sinks(LSHandle* sh, LSMessage* msg, void* ctx)
{
    (void)ctx;

    size_t count = 0;
    const sink_driver_t* const* drivers = sink_drivers(&count);

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_arr_open(&w, "sinks");
    for (size_t i = 0; i < count; i++) {
        jw_obj_open(&w, NULL);
        jw_str(&w, "id", drivers[i]->id);
        jw_str(&w, "name", drivers[i]->name);
        jw_str(&w, "description", drivers[i]->description);
        jw_obj_close(&w);
    }
    jw_arr_close(&w);
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
    return true;
}

static bool method_get_diagnostics(LSHandle* sh, LSMessage* msg, void* ctx)
{
    (void)ctx;

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    capture_write_diagnostics(&w);
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
    return true;
}

static bool method_get_logs(LSHandle* sh, LSMessage* msg, void* ctx)
{
    (void)ctx;

    json_value_t* payload = message_payload(msg);
    bool clear = json_bool(payload, "clear", false);
    json_free(payload);

    char* text = log_dump_recent();

    json_writer_t w;
    jw_init(&w);
    jw_obj_open(&w, NULL);
    jw_bool(&w, "returnValue", true);
    jw_str(&w, "logs", text);
    jw_obj_close(&w);
    reply_json(sh, msg, jw_take(&w));
    free(text);

    if (clear)
        log_clear_recent();
    return true;
}

// Deliberately last: stopping the service is how the UI gets the TV back to a
// clean state without a reboot.
static bool method_quit(LSHandle* sh, LSMessage* msg, void* ctx)
{
    service_t* s = ctx;
    reply_ok(sh, msg);
    INFO("Quit requested over Luna");
    engine_stop(s->engine);
    g_main_loop_quit(s->loop);
    return true;
}

static LSMethod s_methods[] = {
    { "start", method_start, LUNA_METHOD_FLAGS_NONE },
    { "stop", method_stop, LUNA_METHOD_FLAGS_NONE },
    { "getStatus", method_get_status, LUNA_METHOD_FLAGS_NONE },
    { "isRunning", method_is_running, LUNA_METHOD_FLAGS_NONE },
    { "getConfig", method_get_config, LUNA_METHOD_FLAGS_NONE },
    { "setConfig", method_set_config, LUNA_METHOD_FLAGS_NONE },
    { "resetConfig", method_reset_config, LUNA_METHOD_FLAGS_NONE },
    { "listBackends", method_list_backends, LUNA_METHOD_FLAGS_NONE },
    { "listSinks", method_list_sinks, LUNA_METHOD_FLAGS_NONE },
    { "getDiagnostics", method_get_diagnostics, LUNA_METHOD_FLAGS_NONE },
    { "getLogs", method_get_logs, LUNA_METHOD_FLAGS_NONE },
    { "quit", method_quit, LUNA_METHOD_FLAGS_NONE },
    { NULL, NULL, 0 },
};

// ---------------------------------------------------------------------------
// Lifecycle
// ---------------------------------------------------------------------------

service_t* service_create(LSHandle* handle, GMainLoop* loop)
{
    service_t* s = calloc(1, sizeof(*s));
    if (!s)
        return NULL;

    s->handle = handle;
    s->loop = loop;

    s->config = config_load();
    if (!s->config) {
        free(s);
        return NULL;
    }

    const char* level = json_str(config_root(s->config), "logLevel", "info");
    if (strcmp(level, "debug") == 0)
        log_set_level(LOG_DEBUG);
    else if (strcmp(level, "warn") == 0)
        log_set_level(LOG_WARN);
    else if (strcmp(level, "error") == 0)
        log_set_level(LOG_ERROR);

    s->engine = engine_create(on_engine_notify, s);
    if (!s->engine) {
        config_free(s->config);
        free(s);
        return NULL;
    }

    return s;
}

void service_destroy(service_t* s)
{
    if (!s)
        return;
    engine_destroy(s->engine);
    config_free(s->config);
    free(s);
}

bool service_register(service_t* s, char* err, size_t errlen)
{
    LSError lserror;
    LSErrorInit(&lserror);

    if (!LSRegisterCategory(s->handle, "/", s_methods, NULL, NULL, &lserror)) {
        snprintf(err, errlen, "cannot register methods: %s", lserror.message);
        LSErrorFree(&lserror);
        return false;
    }
    if (!LSCategorySetData(s->handle, "/", s, &lserror)) {
        snprintf(err, errlen, "cannot attach service data: %s", lserror.message);
        LSErrorFree(&lserror);
        return false;
    }
    return true;
}

void service_autostart(service_t* s)
{
    if (!json_bool(config_root(s->config), "autoStart", false))
        return;

    char err[256] = { 0 };
    INFO("Autostart is enabled; starting capture");
    if (!engine_start(s->engine, config_root(s->config), err, sizeof(err)))
        ERR("Autostart failed: %s", err);
}