#define PXL8_AUTHORS "asrael <asrael@pxl8.org>"
#define PXL8_COPYRIGHT "Copyright (c) 2024-2025 pxl8.org"
#define PXL8_VERSION "0.1.0"

#include <math.h>
#include <pthread.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>

#include <linenoise.h>

#define SDL_MAIN_USE_CALLBACKS
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>

#include "pxl8_cart.h"
#include "pxl8_macros.h"
#include "pxl8_script.h"
#include "pxl8_types.h"

#define PXL8_MAX_REPL_COMMANDS 4096

typedef struct pxl8_repl_command {
    char buffer[PXL8_MAX_REPL_COMMANDS];
    struct pxl8_repl_command* next;
} pxl8_repl_command;

typedef struct pxl8_repl_state {
    pthread_t thread;
    pthread_mutex_t mutex;
    pxl8_repl_command* queue_head;
    pxl8_repl_command* queue_tail;
    bool running;
} pxl8_repl_state;

typedef struct pxl8_state {
    pxl8_cart* cart;
    pxl8_color_mode color_mode;
    pxl8_gfx* gfx;
    pxl8_repl_state repl;
    pxl8_resolution resolution;
    pxl8_script* script;

    f32 fps_timer;
    i32 frame_count;
    u64 last_time;
    f32 time;

    bool repl_mode;
    bool running;
    bool script_loaded;
    char script_path[256];

    pxl8_input_state input;
} pxl8_state;

static void pxl8_repl_completion(const char* buf, linenoiseCompletions* lc) {
    const char* fennel_keywords[] = {
        "fn", "let", "var", "set", "global", "local", 
        "if", "when", "do", "while", "for", "each",
        "lambda", "λ", "partial", "macro", "macros",
        "require", "include", "import-macros",
        "values", "select", "table", "length",
        ".", "..", ":", "->", "->>", "-?>", "-?>>",
        "doto", "match", "case", "pick-values",
        "collect", "icollect", "accumulate"
    };
    
    const char* pxl8_functions[] = {
        "pxl8.clr", "pxl8.pixel", "pxl8.get_pixel",
        "pxl8.line", "pxl8.rect", "pxl8.rect_fill",
        "pxl8.circle", "pxl8.circle_fill", "pxl8.text",
        "pxl8.get_screen", "pxl8.info", "pxl8.warn",
        "pxl8.error", "pxl8.debug", "pxl8.trace"
    };
    
    auto buf_len = strlen(buf);
    
    for (size_t i = 0; i < sizeof(fennel_keywords) / sizeof(fennel_keywords[0]); i++) {
        if (strncmp(buf, fennel_keywords[i], buf_len) == 0) {
            linenoiseAddCompletion(lc, fennel_keywords[i]);
        }
    }
    
    for (size_t i = 0; i < sizeof(pxl8_functions) / sizeof(pxl8_functions[0]); i++) {
        if (strncmp(buf, pxl8_functions[i], buf_len) == 0) {
            linenoiseAddCompletion(lc, pxl8_functions[i]);
        }
    }
}

static char* pxl8_repl_hints(const char* buf, int* color, int* bold) {
    if (strncmp(buf, "pxl8.", 5) == 0 && strlen(buf) == 5) {
        *color = 35;
        *bold = 0;
        return "clr|pixel|line|rect|circle|text|get_screen";
    }
    
    if (strcmp(buf, "(fn") == 0) {
        *color = 36;
        *bold = 0;
        return " [args] body)";
    }
    
    if (strcmp(buf, "(let") == 0) {
        *color = 36;
        *bold = 0;
        return " [bindings] body)";
    }
    
    return NULL;
}

static void* pxl8_repl_stdin_thread(void* user_data) {
    pxl8_repl_state* repl = (pxl8_repl_state*)user_data;
    char* line;
    const char* history_file = ".pxl8_history";
    
    linenoiseHistorySetMaxLen(100);
    linenoiseSetMultiLine(1);
    linenoiseSetCompletionCallback(pxl8_repl_completion);
    linenoiseSetHintsCallback(pxl8_repl_hints);
    linenoiseHistoryLoad(history_file);
    
    while (repl->running && (line = linenoise(">> "))) {
        if (strlen(line) > 0) {
            linenoiseHistoryAdd(line);
            linenoiseHistorySave(history_file);
            
            pxl8_repl_command* cmd = (pxl8_repl_command*)SDL_malloc(sizeof(pxl8_repl_command));
            if (cmd) {
                strncpy(cmd->buffer, line, PXL8_MAX_REPL_COMMANDS - 1);
                cmd->buffer[PXL8_MAX_REPL_COMMANDS - 1] = '\0';
                cmd->next = NULL;
                
                pthread_mutex_lock(&repl->mutex);
                if (repl->queue_tail) {
                    repl->queue_tail->next = cmd;
                    repl->queue_tail = cmd;
                } else {
                    repl->queue_head = repl->queue_tail = cmd;
                }
                pthread_mutex_unlock(&repl->mutex);
            }
        }
        linenoiseFree(line);
    }
    
    return NULL;
}

static void pxl8_repl_init(pxl8_repl_state* repl) {
    repl->queue_head = NULL;
    repl->queue_tail = NULL;
    repl->running = true;
    pthread_mutex_init(&repl->mutex, NULL);
    pthread_create(&repl->thread, NULL, pxl8_repl_stdin_thread, repl);
}

static void pxl8_repl_shutdown(pxl8_repl_state* repl) {
    repl->running = false;
    pthread_join(repl->thread, NULL);
    pthread_mutex_destroy(&repl->mutex);
    
    pxl8_repl_command* cmd = repl->queue_head;
    while (cmd) {
        pxl8_repl_command* next = cmd->next;
        SDL_free(cmd);
        cmd = next;
    }
}

static pxl8_repl_command* pxl8_repl_pop_command(pxl8_repl_state* repl) {
    pthread_mutex_lock(&repl->mutex);
    pxl8_repl_command* cmd = repl->queue_head;
    if (cmd) {
        repl->queue_head = cmd->next;
        if (!repl->queue_head) {
            repl->queue_tail = NULL;
        }
    }
    pthread_mutex_unlock(&repl->mutex);
    return cmd;
}


SDL_AppResult SDL_AppInit(void** appstate, int argc, char* argv[]) {
    static pxl8_state app = {0};
    
    if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS)) {
        pxl8_error("SDL_Init failed: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }

    app.color_mode = PXL8_COLOR_MODE_MEGA;
    app.resolution = PXL8_RESOLUTION_640x360;

    const char* script_arg = NULL;
    bool pack_mode = false;
    const char* pack_input = NULL;
    const char* pack_output = NULL;

    for (i32 i = 1; i < argc; i++) {
        if (strcmp(argv[i], "--repl") == 0) {
            app.repl_mode = true;
        } else if (strcmp(argv[i], "--pack") == 0) {
            pack_mode = true;
            if (i + 2 < argc) {
                pack_input = argv[++i];
                pack_output = argv[++i];
            } else {
                pxl8_error("--pack requires <folder> <output.pxc>");
                return SDL_APP_FAILURE;
            }
        } else if (!script_arg) {
            script_arg = argv[i];
        }
    }

    if (pack_mode) {
        pxl8_result result = pxl8_cart_pack(pack_input, pack_output);
        return (result == PXL8_OK) ? SDL_APP_SUCCESS : SDL_APP_FAILURE;
    }
    
    
    if (app.repl_mode) {
        fprintf(stderr, "\033[38;2;184;187;38m[pxl8]\033[0m Starting in REPL mode with script: %s\n", app.script_path);
    }

    pxl8_info("Starting up");

    app.gfx = pxl8_gfx_create(app.color_mode, app.resolution, "pxl8", 1280, 720);
    if (!app.gfx) {
        pxl8_error("Failed to create graphics context");
        return SDL_APP_FAILURE;
    }

    if (pxl8_gfx_load_font_atlas(app.gfx) != PXL8_OK) {
        pxl8_error("Failed to load font atlas");
        return SDL_APP_FAILURE;
    }

    if (pxl8_gfx_init_atlas(app.gfx, 1024, 1024) != PXL8_OK) {
        pxl8_error("Failed to initialize sprite atlas");
        return SDL_APP_FAILURE;
    }

    app.script = pxl8_script_create();
    if (!app.script) {
        pxl8_error("Failed to initialize scripting: %s", pxl8_script_get_last_error(app.script));
        pxl8_gfx_destroy(app.gfx);
        return SDL_APP_FAILURE;
    }

    const char* cart_path = script_arg ? script_arg : "demo";

    struct stat st;
    bool is_cart = (stat(cart_path, &st) == 0 && S_ISDIR(st.st_mode)) ||
                   (cart_path && strstr(cart_path, ".pxc"));

    if (is_cart) {
        char* original_cwd = getcwd(NULL, 0);
        app.cart = pxl8_cart_create();
        if (!app.cart) {
            pxl8_error("Failed to create cart");
            return false;
        }
        if (pxl8_cart_load(app.cart, cart_path) == PXL8_OK) {
            pxl8_script_set_cart_path(app.script, pxl8_cart_get_base_path(app.cart), original_cwd);
            pxl8_cart_mount(app.cart);
            strcpy(app.script_path, "main.fnl");
            pxl8_info("Loaded cart: %s", pxl8_cart_get_name(app.cart));
        } else {
            pxl8_error("Failed to load cart: %s", cart_path);
            return SDL_APP_FAILURE;
        }
        free(original_cwd);
    } else if (script_arg) {
        strncpy(app.script_path, script_arg, sizeof(app.script_path) - 1);
        app.script_path[sizeof(app.script_path) - 1] = '\0';
    }

    pxl8_script_set_gfx(app.script, app.gfx);
    pxl8_script_set_input(app.script, &app.input);

    if (app.script_path[0] != '\0') {
        pxl8_result result = pxl8_script_load_main(app.script, app.script_path);
        app.script_loaded = (result == PXL8_OK);
    }
    
    if (app.repl_mode) {
        pxl8_repl_init(&app.repl);
        fprintf(stderr, "\033[38;2;184;187;38m[pxl8 REPL]\033[0m Fennel %s - Tab for completions, Ctrl-C to exit\n", "1.5.1");

        if (pxl8_script_load_module(app.script, "pxl8") != PXL8_OK) {
            fprintf(stderr, "Warning: Failed to setup pxl8 global: %s\n", pxl8_script_get_last_error(app.script));
        }
    }
    
    app.last_time = SDL_GetTicksNS();
    app.running = true;

    *appstate = &app;
    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppIterate(void* appstate) {
    pxl8_state* app = (pxl8_state*)appstate;
    pxl8_bounds bounds = pxl8_gfx_get_bounds(app->gfx);

    u64 current_time = SDL_GetTicksNS();
    f32 dt = (f32)(current_time - app->last_time) / 1000000000.0f;

    app->frame_count++;
    app->fps_timer += dt;
    app->last_time = current_time;
    app->time += dt;

    if (app->fps_timer >= 3.0f) {
        if (!app->repl_mode) {
            f32 avg_fps = app->frame_count / app->fps_timer;
            pxl8_info("FPS: %.1f", avg_fps);
        }
        app->frame_count = 0;
        app->fps_timer = 0.0f;
    }
    
    pxl8_script_check_reload(app->script);
    
    if (app->repl_mode) {
        pxl8_repl_command* cmd = pxl8_repl_pop_command(&app->repl);
        if (cmd) {
            pxl8_result result = pxl8_script_eval(app->script, cmd->buffer);
            if (result != PXL8_OK) {
                pxl8_error("%s", pxl8_script_get_last_error(app->script));
            }
            SDL_free(cmd);
        }
    }

    if (app->script_loaded) {
        pxl8_script_call_function_f32(app->script, "update", dt);

        pxl8_result frame_result = pxl8_script_call_function(app->script, "frame");
        if (frame_result == PXL8_ERROR_SCRIPT_ERROR) {
            pxl8_error("Error calling frame: %s", pxl8_script_get_last_error(app->script));
        }
    } else {
        pxl8_clr(app->gfx, 32);
        
        i32 render_width, render_height;
        pxl8_gfx_get_resolution_dimensions(app->resolution, &render_width, &render_height);
        
        for (i32 y = 0; y < render_height; y += 24) {
            for (i32 x = 0; x < render_width; x += 32) {
                u32 color = ((x / 32) + (y / 24) + (i32)(app->time * 2)) % 8;
                pxl8_rect_fill(app->gfx, x, y, 31, 23, color);
            }
        }
    }
    
    i32 render_width, render_height;
    pxl8_gfx_get_resolution_dimensions(app->resolution, &render_width, &render_height);

    f32 scale = fminf(bounds.w / (f32)render_width, bounds.h / (f32)render_height);
    i32 scaled_width = (i32)(render_width * scale);
    i32 scaled_height = (i32)(render_height * scale);
    i32 offset_x = (bounds.w - scaled_width) / 2;
    i32 offset_y = (bounds.h - scaled_height) / 2;
    
    pxl8_gfx_viewport(app->gfx, offset_x, offset_y, scaled_width, scaled_height);
    pxl8_gfx_upload_framebuffer(app->gfx);
    pxl8_gfx_upload_atlas(app->gfx);
    pxl8_gfx_present(app->gfx);
    
    SDL_memset(app->input.keys_pressed, 0, sizeof(app->input.keys_pressed));

    return app->running ? SDL_APP_CONTINUE : SDL_APP_SUCCESS;
}

SDL_AppResult SDL_AppEvent(void* appstate, SDL_Event* event) {
    pxl8_state* app = (pxl8_state*)appstate;
    
    switch (event->type) {
        case SDL_EVENT_QUIT:
            app->running = false;
            return SDL_APP_SUCCESS;
            
        case SDL_EVENT_KEY_DOWN: {
            if (event->key.key == SDLK_ESCAPE) {
                app->running = false;
                return SDL_APP_SUCCESS;
            }
            
            SDL_Keycode key = event->key.key;
            if (key < 256) {
                if (!app->input.keys[key]) {
                    app->input.keys_pressed[key] = true;
                }
                app->input.keys[key] = true;
            }
            break;
        }
        
        case SDL_EVENT_KEY_UP: {
            SDL_Keycode key = event->key.key;
            if (key < 256) {
                app->input.keys[key] = false;
                app->input.keys_pressed[key] = false;
            }
            break;
        }
    }
    
    return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void* appstate, SDL_AppResult result) {
    pxl8_state* app = (pxl8_state*)appstate;
    (void)result;
    
    if (app) {
        pxl8_info("Shutting down");
        if (app->repl_mode) {
            pxl8_repl_shutdown(&app->repl);
        }
        if (app->cart) {
            pxl8_cart_unload(app->cart);
            free(app->cart);
            app->cart = NULL;
        }
        pxl8_script_destroy(app->script);
        pxl8_gfx_destroy(app->gfx);
    }

    SDL_Quit();
}