#include "core/ReadLine.h"

#include <ctype.h>
#include <stdatomic.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

#include "ErrorSimulator.h"
#include "core/Logger.h"
#include "core/Queue.h"
#include "core/Thread.h"
#include "core/Unicode.h"

static constexpr size_t HISTORY_LENGTH = 10;
static constexpr size_t CONSOLE_BUFFER_SIZE = 256;

typedef struct ConsoleLine {
    char data[CONSOLE_BUFFER_SIZE];
    size_t length;
} ConsoleLine;

QUEUE(ConsoleLine, CL)
QUEUE_SOURCE(ConsoleLine, CL)

static atomic_bool running = true;
static thrd_t readThread = {0};

static QueueCL buffer = {0};
static ConsoleLine currentBuffer = {0};
static size_t move = 0;
static size_t cursorMove = 0;
static mtx_t bufferMutex = {0};

static ConsoleLine history[HISTORY_LENGTH];
static size_t historyOffset = 0;
static size_t historyIndex = 0;
static size_t historyLength = 0;

static void addChar(u64 c) {
    UTF8 u = convertUnicodeToUTF8((u32)c);
    for(u32 k = 0; k < u.length; k++) {
        if(currentBuffer.length >= CONSOLE_BUFFER_SIZE - 1) {
            return;
        }
        for(size_t i = 0; i < move; i++) {
            currentBuffer.data[currentBuffer.length - i] =
                currentBuffer.data[currentBuffer.length - i - 1];
        }
        currentBuffer.length++;
        currentBuffer.data[currentBuffer.length - move - 1] = (char)u.data[k];
        currentBuffer.data[currentBuffer.length] = '\0';
    }
}

static void print(const char* s) {
    fputs(s, stdout);
}

static void refreshLine(const char* prefix) {
    print(prefix);
    print(currentBuffer.data);
    if(cursorMove > 0) {
        moveCursorLeft((int)cursorMove);
    }
    fflush(stdout);
    clearTerminalLine();
}

static bool clear() {
    move = 0;
    cursorMove = 0;
    currentBuffer.length = 0;
    currentBuffer.data[0] = '\0';
    historyOffset = 0;
    return false;
}

static void addToHistory() {
    if(historyLength < HISTORY_LENGTH) {
        historyLength++;
    }
    history[historyIndex] = currentBuffer;
    historyIndex = (historyIndex + 1) % HISTORY_LENGTH;
}

static void lock() {
    if(mtx_lock(&bufferMutex) != thrd_success || MUTEX_LOCK_FAIL) {
        REPORT(LOG_WARNING, "could not lock buffer mutex");
    }
}

static void unlock() {
    if(mtx_unlock(&bufferMutex) != thrd_success || MUTEX_UNLOCK_FAIL) {
        REPORT(LOG_WARNING, "could not unlock buffer mutex");
    }
}

static void addLine() {
    addToHistory();
    lock();
    pushQueueDataCL(&buffer, currentBuffer);
    unlock();
    clear();
}

static bool removeChar() {
    size_t pos = currentBuffer.length - move;
    if(pos > 0) {
        size_t l = 1;
        while(pos - l >= 0) {
            if(!isUTF8Remainder((u8)currentBuffer.data[pos - l])) {
                break;
            }
            l++;
        }
        currentBuffer.length -= l;
        for(size_t i = pos - l; i <= currentBuffer.length; i++) {
            currentBuffer.data[i] = currentBuffer.data[i + l];
        }
    }
    return false;
}

static bool handleControlKey(u64 c) {
    switch(c) {
        case 3: return clear();
        case 10:
        case 13: return true;
        case 127: return removeChar();
    }
    return false;
}

static void copyHistory() {
    currentBuffer = history
        [(historyIndex - historyOffset + HISTORY_LENGTH) % HISTORY_LENGTH];
    move = 0;
    cursorMove = 0;
}

static void handleUpArrow() {
    if(historyOffset >= historyLength) {
        return;
    }
    historyOffset++;
    copyHistory();
}

static void handleDownArrow() {
    if(historyOffset <= 1) {
        return;
    }
    historyOffset--;
    copyHistory();
}

static char getMoved() {
    return currentBuffer.data[currentBuffer.length - move];
}

static void handleLeftArrow() {
    if(move < currentBuffer.length) {
        move++;
        while(move < currentBuffer.length && isUTF8Remainder((u8)getMoved())) {
            move++;
        }
        cursorMove++;
    }
}

static void handleRightArrow() {
    if(move > 0) {
        move--;
        while(move > 0 && isUTF8Remainder((u8)getMoved())) {
            move--;
        }
        cursorMove--;
    }
}

static void handleChars() {
    while(true) {
        u64 c = getRawChar();
        if(c == 0) {
            break;
        } else if(c == TERMINAL_KEY_ARROW_UP) {
            handleUpArrow();
        } else if(c == TERMINAL_KEY_ARROW_DOWN) {
            handleDownArrow();
        } else if(c == TERMINAL_KEY_ARROW_RIGHT) {
            handleRightArrow();
        } else if(c == TERMINAL_KEY_ARROW_LEFT) {
            handleLeftArrow();
        } else if(c == TERMINAL_KEY_DELETE) {
            if(move > 0) {
                handleRightArrow();
                removeChar();
            }
        } else if(iscntrl(c)) {
            if(handleControlKey(c)) {
                addLine();
                return;
            }
        } else {
            addChar(c);
        }
    }
}

static int loop(void* data) {
    (void)data;
    while(running) {
        handleChars();
        refreshLine("wusi> ");
        struct timespec t = {.tv_nsec = 1'000'000};
        thrd_sleep(&t, nullptr);
    }
    return 0;
}

bool startReadLine(void) {
    if(enterRawTerminal()) {
        REPORT(LOG_WARNING, "cannot set terminal attributes");
    }
    initQueueCL(&buffer, 10);
    atomic_store(&running, true);
    if(MUTEX_INIT_FAIL || mtx_init(&bufferMutex, mtx_plain) != thrd_success) {
        REPORT(LOG_ERROR, "cannot init buffer mutex");
        stopReadLine();
        return true;
    } else if(
        THREAD_INIT_FAIL ||
        thrd_create(&readThread, loop, nullptr) != thrd_success) {
        REPORT(LOG_ERROR, "cannot start read thread");
        stopReadLine();
        return true;
    }
    return false;
}

bool readLine(char* buffer_, size_t n) {
    if(buffer.length == 0) {
        return false;
    }
    lock();
    ConsoleLine* line = getQueueIndexCL(&buffer, 0);
    snprintf(buffer_, n, "%s", line->data);
    popQueueDataCL(&buffer);
    unlock();
    return true;
}

void stopReadLine() {
    atomic_store(&running, false);
    joinThreadSafe(&readThread);
    if(leaveRawTerminal()) {
        REPORT(LOG_WARNING, "cannot restore terminal attributes");
    }
    destroyQueueCL(&buffer);
    mtx_destroy(&bufferMutex);
}