#include "SystemFunctions.h"

#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <threads.h>
#include <unistd.h>

#include "Memory.h"
#include "Utils.h"
#include "Window.h"

#define RETURN_INT(value)  \
    *r = INT_VALUE(value); \
    return false

static u32 seed = 0;
static bool rawMode = false;
static struct termios originalTerminal;

static void append(char** buffer, size_t* n, int change) {
    if(change > 0) {
        *buffer += change;
        *n -= (size_t)change;
    }
}

static void printUnicode(const Value* v, char** buffer, size_t* n) {
    UTF8 u = convertUnicodeToUTF8(v->data);
    for(u32 l = 0; l < u.length && *n > 1; l++) {
        **buffer = u.data[l];
        append(buffer, n, 1);
    }
    if(*n > 0) {
        **buffer = '\0';
    }
}

#define APPEND(b, n, format, ...)                                      \
    append(b, n, snprintf(*b, *n, format __VA_OPT__(, ) __VA_ARGS__));

static void printArray(
    const Code* c, const Value* v, char** buffer, size_t* n) {
    if(v->data == -1) {
        APPEND(buffer, n, "null array");
        return;
    }
    Allocation* a = memoryConvertToPointer(v->data);
    Value* end = a->values + a->values[0].data + 1;
    for(Value* i = a->values + 1; i != end; i++) {
        switch(i->type) {
            case VT_INT32: printUnicode(i, buffer, n); break;
            case VT_ARRAY: APPEND(buffer, n, "array"); break;
            case VT_CONSTANT_STRING:
                APPEND(buffer, n, "%s", c->code.data + i->data);
                break;
        }
    }
}

static void print(const Code* c, Value* vs, i32 n, char* buffer, size_t bn) {
    for(i32 i = 0; i < n; i++) {
        Value* v = vs + i;
        switch(v->type) {
            case VT_INT32: APPEND(&buffer, &bn, "%d", v->data); break;
            case VT_ARRAY: printArray(c, v, &buffer, &bn); break;
            case VT_CONSTANT_STRING:
                APPEND(&buffer, &bn, "%s", c->code.data + v->data);
                break;
        }
    }
}

static bool sfPrint(Code* c, Value* r, Value* vs, i32 n) {
    char buffer[1024];
    print(c, vs, n, buffer, sizeof(buffer));
    fputs(buffer, stdout);
    RETURN_INT(0);
}

static bool sfRender(Code* c, Value* r, Value* vs, i32 n) {
    i32 x = vs[0].data;
    i32 y = vs[1].data;
    Color color = (Color)vs[2].data;
    char buffer[1024];
    print(c, vs + 3, n - 3, buffer, sizeof(buffer));
    char* s = buffer;
    while(*s != 0) {
        UTF8 u = {.data = {*(s++)}, .length = 1};
        for(int k = 0; k < 3 && isUTF8Remainder(*s); k++) {
            u.data[u.length] = *s;
            u.length++;
            s++;
        }
        i32 i = convertUTF8toUnicode(u);
        windowSetCharacter(x, y, i, color);
        x += 8;
    }
    RETURN_INT(0);
}

static bool sfPrintLine(Code* c, Value* r, Value* vs, i32 n) {
    bool b = sfPrint(c, r, vs, n);
    putchar('\n');
    return b;
}

#define ESC "\33["
#define esc(s) fputs(ESC s, stdout)

static bool sfClear(Code*, Value* r, Value*, i32) {
    esc("2J");
    RETURN_INT(0);
}

static bool sfGetWidth(Code*, Value* r, Value*, i32) {
    struct winsize w;
    if(ioctl(0, TIOCGWINSZ, &w)) {
        RETURN_INT(0);
    }
    RETURN_INT(w.ws_col);
}

static bool sfGetHeight(Code*, Value* r, Value*, i32) {
    struct winsize w;
    if(ioctl(0, TIOCGWINSZ, &w)) {
        RETURN_INT(0);
    }
    RETURN_INT(w.ws_row);
}

static bool sfClearLine(Code*, Value* r, Value*, i32) {
    esc("2K\r");
    RETURN_INT(0);
}

static bool sfHideCursor(Code*, Value* r, Value*, i32) {
    esc("?25l");
    RETURN_INT(0);
}

static bool sfShowCursor(Code*, Value* r, Value*, i32) {
    esc("?25h");
    RETURN_INT(0);
}

static bool sfResetCursor(Code*, Value* r, Value*, i32) {
    esc("H");
    RETURN_INT(0);
}

static bool sfMoveCursorLeft(Code*, Value* r, Value* vs, i32) {
    if(vs[0].data > 0) {
        printf(ESC "%dD", vs[0].data);
    }
    RETURN_INT(0);
}

static bool sfMoveCursorRight(Code*, Value* r, Value* vs, i32) {
    if(vs[0].data > 0) {
        printf(ESC "%dC", vs[0].data);
    }
    RETURN_INT(0);
}

static bool sfMoveCursorUp(Code*, Value* r, Value* vs, i32) {
    if(vs[0].data > 0) {
        printf(ESC "%dA", vs[0].data);
    }
    RETURN_INT(0);
}

static bool sfMoveCursorDown(Code*, Value* r, Value* vs, i32) {
    if(vs[0].data > 0) {
        printf(ESC "%dB", vs[0].data);
    }
    RETURN_INT(0);
}

static bool sfSleep(Code*, Value* r, Value* vs, i32) {
    struct timespec t = {.tv_sec = vs[0].data, .tv_nsec = vs[1].data};
    thrd_sleep(&t, nullptr);
    RETURN_INT(0);
}

static bool sfRandom(Code*, Value* r, Value* vs, i32) {
    seed = seed * 1664525u + 1013904223u;
    u32 s = seed % (u32)(vs[1].data + 1 - vs[0].data);
    RETURN_INT(vs[0].data + (i32)s);
}

static bool codeAllocate(Code* c, Value* v, i32 n) {
    v->type = VT_ARRAY;
    v->data = -1;
    if(n <= 0) {
        return false;
    }
    codeRunCollector(c);
    size_t s = sizeof(Allocation) + ((size_t)n + 1) * sizeof(Value);
    Allocation* a = memoryAllocate(s);
    if(a == nullptr) {
        SET_ERROR("Out of memory");
        return true;
    }
    memset(a, 0, s);
    a->next = c->allocations;
    c->allocations = a;
    a->values[0].type = VT_INT32;
    a->values[0].data = n;
    v->data = memoryConvertToIndex(a);
    return false;
}

static bool sfArray(Code* c, Value* r, Value* vs, i32) {
    return codeAllocate(c, r, vs[0].data);
}

static bool sfGetAllocations(Code* c, Value* r, Value*, i32) {
    codeRunCollector(c);
    i32 counter = 0;
    for(Allocation* a = c->allocations; a != nullptr; a = a->next) {
        counter++;
    }
    RETURN_INT(counter);
}

static bool sfEnterRawTerminal(Code* c, Value* r, Value*, i32) {
    if(rawMode) {
        RETURN_INT(0);
    }
    if(tcgetattr(STDIN_FILENO, &originalTerminal)) {
        SET_ERROR("Cannot safe current terminal mode");
        return true;
    }
    struct termios raw = originalTerminal;
    raw.c_iflag &= ~(tcflag_t)(ICRNL | IXON);
    raw.c_lflag &= ~(tcflag_t)(ECHO | ICANON | IEXTEN | ISIG);
    raw.c_cc[VMIN] = 0;
    raw.c_cc[VTIME] = 0;
    if(tcsetattr(STDIN_FILENO, TCSANOW, &raw)) {
        SET_ERROR("Cannot enter raw terminal mode");
        return true;
    }
    RETURN_INT(0);
}

static bool sfLeaveRawTerminal(Code* c, Value* r, Value*, i32) {
    if(!rawMode) {
        RETURN_INT(0);
    }
    if(tcsetattr(STDIN_FILENO, TCSAFLUSH, &originalTerminal)) {
        SET_ERROR("Cannot leave raw terminal mode");
        return true;
    }
    RETURN_INT(0);
}

static bool sfReadChar(Code*, Value* r, Value*, i32) {
    u8 ch = 0;
    ssize_t bytes = read(STDIN_FILENO, &ch, 1);
    RETURN_INT(bytes <= 0 ? '\0' : ch);
}

static bool sfFlush(Code*, Value* r, Value*, i32) {
    fflush(stdout);
    RETURN_INT(0);
}

static bool sfWindowInit(Code* c, Value* r, Value* vs, i32) {
    WindowSettings ws = {
        .width = vs[0].data, .height = vs[1].data, .title = "Dummy"};
    c->error = windowInit(&ws);
    *r = INT_VALUE(0);
    return hasError(&c->error);
}

#define WINDOW_CHECK()                     \
    do {                                   \
        if(!windowExists()) {              \
            SET_ERROR("No window exists"); \
            return true;                   \
        }                                  \
    } while(false)

static bool sfWindowShouldClose(Code* c, Value* r, Value*, i32) {
    WINDOW_CHECK();
    RETURN_INT(windowShouldClose());
}

static bool sfWindowNextFrame(Code* c, Value* r, Value*, i32) {
    WINDOW_CHECK();
    windowNextFrame();
    RETURN_INT(0);
}

static bool sfWindowClear(Code* c, Value* r, Value* vs, i32) {
    WINDOW_CHECK();
    windowClear((Color)vs[0].data);
    RETURN_INT(0);
}

static bool sfWindowSetPixel(Code* c, Value* r, Value* vs, i32) {
    WINDOW_CHECK();
    windowSetPixel(vs[0].data, vs[1].data, (Color)vs[2].data);
    RETURN_INT(0);
}

static bool sfColor(Code*, Value* r, Value* vs, i32) {
    RETURN_INT(COLOR(vs[0].data, vs[1].data, vs[2].data));
}

static bool sfGetRed(Code*, Value* r, Value* vs, i32) {
    RETURN_INT((vs[0].data & 0b1111100000000000) >> 11);
}

static bool sfGetGreen(Code*, Value* r, Value* vs, i32) {
    RETURN_INT((vs[0].data & 0b11111000000) >> 6);
}

static bool sfGetBlue(Code*, Value* r, Value* vs, i32) {
    RETURN_INT((vs[0].data & 0b111110) >> 1);
}

static bool sfIsButtonDown(Code*, Value* r, Value* vs, i32) {
    RETURN_INT(isButtonDown((Button)vs[0].data));
}

static bool sfGetButtonDownTime(Code*, Value* r, Value* vs, i32) {
    RETURN_INT(getButtonDownTime((Button)vs[0].data));
}

typedef struct {
    SystemFunction function;
    i32 arguments;
    const char* name;
} FunctionEntry;

static FunctionEntry systemFunctions[] = {
    {sfPrint, -1, "print"},
    {sfPrintLine, -1, "printLine"},
    {sfClear, 0, "clear"},
    {sfSleep, 2, "sleep"},
    {sfGetWidth, 0, "getWidth"},
    {sfGetHeight, 0, "getHeight"},
    {sfClearLine, 0, "clearLine"},
    {sfHideCursor, 0, "hideCursor"},
    {sfShowCursor, 0, "showCursor"},
    {sfResetCursor, 0, "resetCursor"},
    {sfMoveCursorLeft, 1, "moveCursorLeft"},
    {sfMoveCursorRight, 1, "moveCursorRight"},
    {sfMoveCursorUp, 1, "moveCursorUp"},
    {sfMoveCursorDown, 1, "moveCursorDown"},
    {sfRandom, 2, "random"},
    {sfArray, 1, "array"},
    {sfGetAllocations, 0, "getAllocations"},
    {sfEnterRawTerminal, 0, "enterRawTerminal"},
    {sfLeaveRawTerminal, 0, "leaveRawTerminal"},
    {sfReadChar, 0, "readChar"},
    {sfFlush, 0, "flush"},
    {sfWindowInit, 2, "initWindow"},
    {sfWindowShouldClose, 0, "shouldClose"},
    {sfWindowNextFrame, 0, "nextFrame"},
    {sfWindowClear, 1, "clearWindow"},
    {sfWindowSetPixel, 3, "setPixel"},
    {sfColor, 3, "color"},
    {sfGetRed, 1, "getRed"},
    {sfGetGreen, 1, "getGreen"},
    {sfGetBlue, 1, "getBlue"},
    {sfIsButtonDown, 1, "isButtonDown"},
    {sfGetButtonDownTime, 1, "getButtonDownTime"},
    {sfRender, -4, "render"},
};
static constexpr i32 amount = sizeof(systemFunctions) / sizeof(FunctionEntry);

i32 getSystemFunctionIndex(const char* s) {
    for(i32 i = 0; i < amount; i++) {
        if(strcmp(systemFunctions[i].name, s) == 0) {
            return i;
        }
    }
    return -1;
}

i32 getSystemFunctionArguments(i32 index) {
    if(index >= 0 && index < amount) {
        return systemFunctions[index].arguments;
    }
    return -1;
}

SystemFunction getSystemFunction(i32 index) {
    if(index >= 0 && index < amount) {
        return systemFunctions[index].function;
    }
    return nullptr;
}

void initSystemFunctions() {
    struct timespec t = {};
    timespec_get(&t, TIME_UTC);
    seed = (u32)t.tv_nsec;
}