#include <malloc.h>
#include <assert.h>
#include <esp_log.h>
#include <rom/queue.h>

#include "liquid.h"
#include "nokia.h"

static const char *TAG = "Liquid";

extern struct Scene *NewScene_Root(void);
static struct SceneEvent Liquid_initTopScene(struct Liquid *container);
static bool processReturnValue(struct Liquid *container, struct SceneEvent result);

struct RunningScene {
    struct Scene *scene;
    SLIST_ENTRY(RunningScene) next;
} cmd_item_t;

struct Liquid {
    SLIST_HEAD(, RunningScene) stack; // stack with the topmost scene as the first element / head
};

static struct SceneEvent Default_onChildReturn(struct Scene *scene, uint32_t tag, int32_t status, void *data) {
    if (data) free(data);
    return SceneEvent_Repaint();
}

static void addChild(struct Liquid *container, struct Scene *child) {
    struct RunningScene *elm = calloc(1, sizeof(struct RunningScene));
    if (!child->onChildReturn) child->onChildReturn = Default_onChildReturn;
    elm->scene = child;
    SLIST_INSERT_HEAD(&container->stack, elm, next);
}

struct Liquid *Liquid_start(void) {
    struct Liquid *container = calloc(1, sizeof(struct Liquid));

    addChild(container, NewScene_Root());

    struct SceneEvent result = Liquid_initTopScene(container);

    if (processReturnValue(container, result)) {
        Liquid_paint(container);
    }
    return container;
}

static struct SceneEvent handleSceneEvent(struct Liquid *container, struct SceneEvent event) {
    struct RunningScene *topmost = SLIST_FIRST(&container->stack);
    struct Scene *newScene;
    uint32_t tag;
    switch (event.kind) {
        case SceneEventKind_Close:
            assert(SLIST_NEXT(topmost, next) != NULL);
            SLIST_REMOVE_HEAD(&container->stack, next);
            tag = topmost->scene->tag;

            if (topmost->scene->free) {
                topmost->scene->free(topmost->scene);
            }
            free(topmost->scene);
            free(topmost);

            topmost = SLIST_FIRST(&container->stack);

            // this is always set.
            return topmost->scene->onChildReturn(topmost->scene, tag, event.close.status, event.close.data);

        case SceneEventKind_OpenChild:
            if (!event.open.scene) {
                ESP_LOGE(TAG, "Attempt to open NULL scene!");
                return SceneEvent_None();
            }
            newScene = event.open.scene;
            newScene->tag = event.open.tag;
            addChild(container, newScene);
            return Liquid_initTopScene(container);

        case SceneEventKind_RequestRepaint:
        case SceneEventKind_None:
        default:
            // this shouldn't get here
            return event;
    }
}

/**
 * returns true if repaint is requested
 */
static bool processReturnValue(struct Liquid *container, struct SceneEvent result) {
    bool repaint = false;
    while (result.kind != SceneEventKind_None) {
        if (result.kind == SceneEventKind_RequestRepaint) {
            // Repaint explicitly requested, there's no more chained events.
            repaint = true;
            break;
        }
        if (result.kind == SceneEventKind_Close) {
            // child close always triggers repaint, but the event handler can return
            // another event (e.g. close itself, or open a new child).
            repaint = true;
        }
        // one event can lead to another...
        result = handleSceneEvent(container, result);
    }
    return repaint;
}

bool Liquid_handleInput(struct Liquid *container, struct InputEvent event) {
    struct RunningScene *topmost = SLIST_FIRST(&container->stack);
    assert(topmost != NULL);
    assert(topmost->scene != NULL);
    if (topmost->scene->onInput) {
        struct SceneEvent result = topmost->scene->onInput(topmost->scene, event);
        return processReturnValue(container, result);
    } else {
        return false;
    }
}

bool Liquid_handleTick(struct Liquid *container, uint32_t elapsed_millis) {
    struct RunningScene *topmost = SLIST_FIRST(&container->stack);
    assert(topmost != NULL);
    assert(topmost->scene != NULL);
    if (topmost->scene->onTick) {
        struct SceneEvent result = topmost->scene->onTick(topmost->scene, elapsed_millis);
        return processReturnValue(container, result);
    } else {
        return false;
    }
}

static struct SceneEvent Liquid_initTopScene(struct Liquid *container) {
    struct RunningScene *topmost = SLIST_FIRST(&container->stack);
    assert(topmost != NULL);
    assert(topmost->scene != NULL);
    if (topmost->scene->init) {
        return topmost->scene->init(topmost->scene);
    } else {
        return SceneEvent_Repaint();
    }
}

void Liquid_paint(struct Liquid *container) {
    struct RunningScene *topmost = SLIST_FIRST(&container->stack);
    assert(topmost != NULL);
    if (topmost->scene->paint) {
        topmost->scene->paint(topmost->scene);
    }

    LCD_updateDisplay();
}