#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <ctype.h>
#include <stdarg.h>

#include <iostream>
#include <fstream>
#include <string>
#include <cstring>

#include "editor.hpp"
#include "environment.hpp"

/*** defines ***/

#define KILO_VERSION "0.0.1"
#define KILO_TAB_STOP 8
#define KILO_QUIT_TIMES 3

#define CTRL_KEY(k) ((k) & 0x1f)

enum editorKey
{
  BACKSPACE = 127,
  ARROW_LEFT = 1000,
  ARROW_RIGHT,
  ARROW_UP,
  ARROW_DOWN,
  DEL_KEY,
  HOME_KEY,
  END_KEY,
  PAGE_UP,
  PAGE_DOWN
};

/*** data ***/

typedef struct erow
{
  int idx;
  int size;
  int rsize;
  char *chars;
  char *render;
} erow;

struct editorConfig
{
  int cx, cy;
  int rx;
  int rowoff;
  int coloff;
  int screenrows;
  int screencols;
  int numrows;
  erow *row;
  int dirty;
  char *filename;
  char statusmsg[80];
  time_t statusmsg_time;
  bool running;
};

struct editorConfig E;

/*** prototypes ***/

void editorSetStatusMessage(const char *fmt, ...);
void editorRefreshScreen();
char *editorPrompt(const char *prompt, void (*callback)(char *, int));

/*** terminal ***/

void die(const char *s)
{
  writeTerm("\x1b[2J", 4);
  writeTerm("\x1b[H", 3);
  perror(s);
  E.running = false;
}

int editorReadKey()
{
  int nread;
  char c;
  while ((nread = readTerm(&c, 1)) != 1)
  {
    if (nread == -1 && errno != EAGAIN)
      die("read");
  }

  if (c == '\x1b')
  {
    char seq[3];

    if (readTerm(&seq[0], 1) != 1)
      return '\x1b';
    if (readTerm(&seq[1], 1) != 1)
      return '\x1b';

    if (seq[0] == '[')
    {
      if (seq[1] >= '0' && seq[1] <= '9')
      {
        if (readTerm(&seq[2], 1) != 1)
          return '\x1b';
        if (seq[2] == '~')
        {
          switch (seq[1])
          {
          case '1':
            return HOME_KEY;
          case '3':
            return DEL_KEY;
          case '4':
            return END_KEY;
          case '5':
            return PAGE_UP;
          case '6':
            return PAGE_DOWN;
          case '7':
            return HOME_KEY;
          case '8':
            return END_KEY;
          }
        }
      }
      else
      {
        switch (seq[1])
        {
        case 'A':
          return ARROW_UP;
        case 'B':
          return ARROW_DOWN;
        case 'C':
          return ARROW_RIGHT;
        case 'D':
          return ARROW_LEFT;
        case 'H':
          return HOME_KEY;
        case 'F':
          return END_KEY;
        }
      }
    }
    else if (seq[0] == 'O')
    {
      switch (seq[1])
      {
      case 'H':
        return HOME_KEY;
      case 'F':
        return END_KEY;
      }
    }

    return '\x1b';
  }
  else
  {
    return c;
  }
}

/*** row operations ***/

int editorRowCxToRx(erow *row, int cx)
{
  int rx = 0;
  int j;
  for (j = 0; j < cx; j++)
  {
    if (row->chars[j] == '\t')
      rx += (KILO_TAB_STOP - 1) - (rx % KILO_TAB_STOP);
    rx++;
  }
  return rx;
}

int editorRowRxToCx(erow *row, int rx)
{
  int cur_rx = 0;
  int cx;
  for (cx = 0; cx < row->size; cx++)
  {
    if (row->chars[cx] == '\t')
      cur_rx += (KILO_TAB_STOP - 1) - (cur_rx % KILO_TAB_STOP);
    cur_rx++;

    if (cur_rx > rx)
      return cx;
  }
  return cx;
}

void editorUpdateRow(erow *row)
{
  int tabs = 0;
  int j;
  for (j = 0; j < row->size; j++)
    if (row->chars[j] == '\t')
      tabs++;

  free(row->render);
  row->render = (char *)malloc(row->size + tabs * (KILO_TAB_STOP - 1) + 1);

  int idx = 0;
  for (j = 0; j < row->size; j++)
  {
    if (row->chars[j] == '\t')
    {
      row->render[idx++] = ' ';
      while (idx % KILO_TAB_STOP != 0)
        row->render[idx++] = ' ';
    }
    else
    {
      row->render[idx++] = row->chars[j];
    }
  }
  row->render[idx] = '\0';
  row->rsize = idx;
}

void editorInsertRow(int at, const char *s, size_t len)
{
  if (at < 0 || at > E.numrows)
    return;

  E.row = (erow *)realloc(E.row, sizeof(erow) * (E.numrows + 1));
  memmove(&E.row[at + 1], &E.row[at], sizeof(erow) * (E.numrows - at));
  for (int j = at + 1; j <= E.numrows; j++)
    E.row[j].idx++;

  E.row[at].idx = at;

  E.row[at].size = len;
  E.row[at].chars = (char *)malloc(len + 1);
  memcpy(E.row[at].chars, s, len);
  E.row[at].chars[len] = '\0';

  E.row[at].rsize = 0;
  E.row[at].render = NULL;
  editorUpdateRow(&E.row[at]);

  E.numrows++;
  E.dirty++;
}

void editorFreeRow(erow *row)
{
  free(row->render);
  free(row->chars);
}

void editorDelRow(int at)
{
  if (at < 0 || at >= E.numrows)
    return;
  editorFreeRow(&E.row[at]);
  memmove(&E.row[at], &E.row[at + 1], sizeof(erow) * (E.numrows - at - 1));
  for (int j = at; j < E.numrows - 1; j++)
    E.row[j].idx--;
  E.numrows--;
  E.dirty++;
}

void editorRowInsertChar(erow *row, int at, int c)
{
  if (at < 0 || at > row->size)
    at = row->size;
  row->chars = (char *)realloc(row->chars, row->size + 2);
  memmove(&row->chars[at + 1], &row->chars[at], row->size - at + 1);
  row->size++;
  row->chars[at] = c;
  editorUpdateRow(row);
  E.dirty++;
}

void editorRowAppendString(erow *row, char *s, size_t len)
{
  row->chars = (char *)realloc(row->chars, row->size + len + 1);
  memcpy(&row->chars[row->size], s, len);
  row->size += len;
  row->chars[row->size] = '\0';
  editorUpdateRow(row);
  E.dirty++;
}

void editorRowDelChar(erow *row, int at)
{
  if (at < 0 || at >= row->size)
    return;
  memmove(&row->chars[at], &row->chars[at + 1], row->size - at);
  row->size--;
  editorUpdateRow(row);
  E.dirty++;
}

/*** editor operations ***/

void editorInsertChar(int c)
{
  if (E.cy == E.numrows)
  {
    editorInsertRow(E.numrows, "", 0);
  }
  editorRowInsertChar(&E.row[E.cy], E.cx, c);
  E.cx++;
}

void editorInsertNewline()
{
  if (E.cx == 0)
  {
    editorInsertRow(E.cy, "", 0);
  }
  else
  {
    erow *row = &E.row[E.cy];
    editorInsertRow(E.cy + 1, &row->chars[E.cx], row->size - E.cx);
    row = &E.row[E.cy];
    row->size = E.cx;
    row->chars[row->size] = '\0';
    editorUpdateRow(row);
  }
  E.cy++;
  E.cx = 0;
}

void editorDelChar()
{
  if (E.cy == E.numrows)
    return;
  if (E.cx == 0 && E.cy == 0)
    return;

  erow *row = &E.row[E.cy];
  if (E.cx > 0)
  {
    editorRowDelChar(row, E.cx - 1);
    E.cx--;
  }
  else
  {
    E.cx = E.row[E.cy - 1].size;
    editorRowAppendString(&E.row[E.cy - 1], row->chars, row->size);
    editorDelRow(E.cy);
    E.cy--;
  }
}

/*** file i/o ***/

char *editorRowsToString(int *buflen)
{
  int totlen = 0;
  int j;
  for (j = 0; j < E.numrows; j++)
    totlen += E.row[j].size + 1; // +1 for new line
  totlen += 1;                   // +1 for null termination
  *buflen = totlen;

  char *buf = (char *)malloc(totlen);
  char *p = buf;
  for (j = 0; j < E.numrows; j++)
  {
    memcpy(p, E.row[j].chars, E.row[j].size);
    p += E.row[j].size;
    *p = '\n';
    p++;
  }
  *p = '\0';
  return buf;
}

void editorOpen(const char *data)
{
  size_t start = 0;
  size_t end = 0;

  for (end = 0; data[end] != '\0'; end++)
  {
    if (data[end] == '\n')
    {
      editorInsertRow(E.numrows, &data[start], end - start);
      start = end + 1;
    }
  }

  editorInsertRow(E.numrows, &data[start], end - start);
  E.dirty = 0;
}

void editorSave()
{
  if (E.filename == NULL)
  {
    E.filename = editorPrompt("Save as: %s (ESC to cancel)", NULL);
    if (E.filename == NULL)
    {
      editorSetStatusMessage("Save aborted");
      return;
    }
  }

  int len;
  char *buf = editorRowsToString(&len);

  std::ofstream file(E.filename, std::ios::binary | std::ios::out);
  if (!file.is_open())
  {
    free(buf);
    editorSetStatusMessage("Can't save! I/O error");
    return;
  }
  file.write(buf, len);
  file.close();

  free(buf);
  editorSetStatusMessage("Saved to disk");
  E.dirty = 0;
}

/*** find ***/

void editorFindCallback(char *query, int key)
{
  static int last_match = -1;
  static int direction = 1;

  if (key == '\r' || key == '\x1b')
  {
    last_match = -1;
    direction = 1;
    return;
  }
  else if (key == ARROW_RIGHT || key == ARROW_DOWN)
  {
    direction = 1;
  }
  else if (key == ARROW_LEFT || key == ARROW_UP)
  {
    direction = -1;
  }
  else
  {
    last_match = -1;
    direction = 1;
  }

  if (last_match == -1)
    direction = 1;
  int current = last_match;
  int i;
  for (i = 0; i < E.numrows; i++)
  {
    current += direction;
    if (current == -1)
      current = E.numrows - 1;
    else if (current == E.numrows)
      current = 0;

    erow *row = &E.row[current];
    char *match = strstr(row->render, query);
    if (match)
    {
      last_match = current;
      E.cy = current;
      E.cx = editorRowRxToCx(row, match - row->render);
      E.rowoff = E.numrows;
      break;
    }
  }
}

void editorFind()
{
  int saved_cx = E.cx;
  int saved_cy = E.cy;
  int saved_coloff = E.coloff;
  int saved_rowoff = E.rowoff;

  char *query = editorPrompt("Search: %s (Use ESC/Arrows/Enter)", editorFindCallback);

  if (query)
  {
    free(query);
  }
  else
  {
    E.cx = saved_cx;
    E.cy = saved_cy;
    E.coloff = saved_coloff;
    E.rowoff = saved_rowoff;
  }
}

/*** append buffer ***/

struct abuf
{
  char *b;
  int len;
  int size;
};

#define ABUF_INIT {NULL, 0, 0}

void abAppend(struct abuf *ab, const char *s, int len)
{
  if (ab->len + len > ab->size)
  {
    ab->size = (ab->len + len) * 2;
    ab->b = (char *)realloc(ab->b, ab->size);
  }
  memcpy(&ab->b[ab->len], s, len);
  ab->len += len;
}

void abFree(struct abuf *ab)
{
  free(ab->b);
}

/*** output ***/

void editorScroll()
{
  E.rx = 0;
  if (E.cy < E.numrows)
  {
    E.rx = editorRowCxToRx(&E.row[E.cy], E.cx);
  }

  if (E.cy < E.rowoff)
  {
    E.rowoff = E.cy;
  }
  if (E.cy >= E.rowoff + E.screenrows)
  {
    E.rowoff = E.cy - E.screenrows + 1;
  }
  if (E.rx < E.coloff)
  {
    E.coloff = E.rx;
  }
  if (E.rx >= E.coloff + E.screencols)
  {
    E.coloff = E.rx - E.screencols + 1;
  }
}

void editorDrawRows(struct abuf *ab)
{
  int y;
  for (y = 0; y < E.screenrows; y++)
  {
    int filerow = y + E.rowoff;
    if (filerow >= E.numrows)
    {
      if (E.numrows == 0 && y == E.screenrows / 3)
      {
        char welcome[80];
        int welcomelen = snprintf(welcome, sizeof(welcome),
                                  "Kilo editor -- version %s", KILO_VERSION);
        if (welcomelen > E.screencols)
          welcomelen = E.screencols;
        int padding = (E.screencols - welcomelen) / 2;
        if (padding)
        {
          abAppend(ab, "~", 1);
          padding--;
        }
        while (padding--)
          abAppend(ab, " ", 1);
        abAppend(ab, welcome, welcomelen);
      }
      else
      {
        abAppend(ab, "~", 1);
      }
    }
    else
    {
      int len = E.row[filerow].rsize - E.coloff;
      if (len < 0)
        len = 0;
      if (len > E.screencols)
        len = E.screencols;
      char *c = &E.row[filerow].render[E.coloff];
      int current_color = -1;
      int j;
      for (j = 0; j < len; j++)
      {
        if (iscntrl(c[j]))
        {
          char sym = (c[j] <= 26) ? '@' + c[j] : '?';
          abAppend(ab, "\x1b[7m", 4);
          abAppend(ab, &sym, 1);
          abAppend(ab, "\x1b[m", 3);
          if (current_color != -1)
          {
            char buf[16];
            int clen = snprintf(buf, sizeof(buf), "\x1b[%dm", current_color);
            abAppend(ab, buf, clen);
          }
        }
        else
        {
          if (current_color != -1)
          {
            abAppend(ab, "\x1b[39m", 5);
            current_color = -1;
          }
          abAppend(ab, &c[j], 1);
        }
      }
      abAppend(ab, "\x1b[39m", 5);
    }

    abAppend(ab, "\x1b[K", 3);
    abAppend(ab, "\r\n", 2);
  }
}

void editorDrawStatusBar(struct abuf *ab)
{
  abAppend(ab, "\x1b[7m", 4);
  char status[80], rstatus[80];
  int len = snprintf(status, sizeof(status), "%.20s - %d lines %s",
                     E.filename ? E.filename : "[No Name]", E.numrows,
                     E.dirty ? "(modified)" : "");
  int rlen = snprintf(rstatus, sizeof(rstatus), "%s | %d/%d",
                      "no ft", E.cy + 1, E.numrows);
  if (len > E.screencols)
    len = E.screencols;
  abAppend(ab, status, len);
  while (len < E.screencols)
  {
    if (E.screencols - len == rlen)
    {
      abAppend(ab, rstatus, rlen);
      break;
    }
    else
    {
      abAppend(ab, " ", 1);
      len++;
    }
  }
  abAppend(ab, "\x1b[m", 3);
  abAppend(ab, "\r\n", 2);
}

void editorDrawMessageBar(struct abuf *ab)
{
  abAppend(ab, "\x1b[K", 3);
  int msglen = strlen(E.statusmsg);
  if (msglen > E.screencols)
    msglen = E.screencols;
  if (msglen && time(NULL) - E.statusmsg_time < 5)
    abAppend(ab, E.statusmsg, msglen);
}

void editorRefreshScreen()
{
  editorScroll();

  struct abuf ab = ABUF_INIT;

  abAppend(&ab, "\x1b[?25l", 6);
  abAppend(&ab, "\x1b[H", 3);

  editorDrawRows(&ab);
  editorDrawStatusBar(&ab);
  editorDrawMessageBar(&ab);

  char buf[32];
  snprintf(buf, sizeof(buf), "\x1b[%d;%dH", (E.cy - E.rowoff) + 1,
           (E.rx - E.coloff) + 1);
  abAppend(&ab, buf, strlen(buf));

  abAppend(&ab, "\x1b[?25h", 6);

  writeTerm(ab.b, ab.len);
  abFree(&ab);
}

void editorSetStatusMessage(const char *fmt, ...)
{
  va_list ap;
  va_start(ap, fmt);
  vsnprintf(E.statusmsg, sizeof(E.statusmsg), fmt, ap);
  va_end(ap);
  E.statusmsg_time = time(NULL);
}

/*** input ***/

char *editorPrompt(const char *prompt, void (*callback)(char *, int))
{
  size_t bufsize = 128;
  char *buf = (char *)malloc(bufsize);

  size_t buflen = 0;
  buf[0] = '\0';

  while (E.running)
  {
    editorSetStatusMessage(prompt, buf);
    editorRefreshScreen();

    int c = editorReadKey();
    if (c == DEL_KEY || c == CTRL_KEY('h') || c == BACKSPACE)
    {
      if (buflen != 0)
        buf[--buflen] = '\0';
    }
    else if (c == '\x1b')
    {
      editorSetStatusMessage("");
      if (callback)
        callback(buf, c);
      free(buf);
      return NULL;
    }
    else if (c == '\r')
    {
      if (buflen != 0)
      {
        editorSetStatusMessage("");
        if (callback)
          callback(buf, c);
        return buf;
      }
    }
    else if (!iscntrl(c) && c < 128)
    {
      if (buflen == bufsize - 1)
      {
        bufsize *= 2;
        buf = (char *)realloc(buf, bufsize);
      }
      buf[buflen++] = c;
      buf[buflen] = '\0';
    }

    if (callback)
      callback(buf, c);
  }
  return NULL;
}

void editorMoveCursor(int key)
{
  erow *row = (E.cy >= E.numrows) ? NULL : &E.row[E.cy];

  switch (key)
  {
  case ARROW_LEFT:
    if (E.cx != 0)
    {
      E.cx--;
    }
    else if (E.cy > 0)
    {
      E.cy--;
      E.cx = E.row[E.cy].size;
    }
    break;
  case ARROW_RIGHT:
    if (row && E.cx < row->size)
    {
      E.cx++;
    }
    else if (row && E.cx == row->size)
    {
      E.cy++;
      E.cx = 0;
    }
    break;
  case ARROW_UP:
    if (E.cy != 0)
    {
      E.cy--;
    }
    break;
  case ARROW_DOWN:
    if (E.cy < E.numrows)
    {
      E.cy++;
    }
    break;
  }

  row = (E.cy >= E.numrows) ? NULL : &E.row[E.cy];
  int rowlen = row ? row->size : 0;
  if (E.cx > rowlen)
  {
    E.cx = rowlen;
  }
}

void editorProcessKeypress()
{
  static int quit_times = KILO_QUIT_TIMES;

  int c = editorReadKey();

  switch (c)
  {
  case '\r':
    editorInsertNewline();
    break;

  case CTRL_KEY('q'):
    if (E.dirty && quit_times > 0)
    {
      editorSetStatusMessage("WARNING!!! File has unsaved changes. "
                             "Press Ctrl-Q %d more times to quit.",
                             quit_times);
      quit_times--;
      return;
    }
    writeTerm("\x1b[2J", 4);
    writeTerm("\x1b[H", 3);
    E.running = false;
    break;

  case CTRL_KEY('s'):
    editorSave();
    break;

  case HOME_KEY:
    E.cx = 0;
    break;

  case END_KEY:
    if (E.cy < E.numrows)
      E.cx = E.row[E.cy].size;
    break;

  case CTRL_KEY('f'):
    editorFind();
    break;

  case BACKSPACE:
  case CTRL_KEY('h'):
  case DEL_KEY:
    if (c == DEL_KEY)
      editorMoveCursor(ARROW_RIGHT);
    editorDelChar();
    break;

  case PAGE_UP:
  case PAGE_DOWN:
  {
    if (c == PAGE_UP)
    {
      E.cy = E.rowoff;
    }
    else if (c == PAGE_DOWN)
    {
      E.cy = E.rowoff + E.screenrows - 1;
      if (E.cy > E.numrows)
        E.cy = E.numrows;
    }

    int times = E.screenrows;
    while (times--)
      editorMoveCursor(c == PAGE_UP ? ARROW_UP : ARROW_DOWN);
  }
  break;

  case ARROW_UP:
  case ARROW_DOWN:
  case ARROW_LEFT:
  case ARROW_RIGHT:
    editorMoveCursor(c);
    break;

  case CTRL_KEY('l'):
  case '\x1b':
    break;

  default:
    editorInsertChar(c);
    break;
  }

  quit_times = KILO_QUIT_TIMES;
}

/*** init ***/

void initEditor()
{
  E.cx = 0;
  E.cy = 0;
  E.rx = 0;
  E.rowoff = 0;
  E.coloff = 0;
  E.numrows = 0;
  E.row = NULL;
  E.dirty = 0;
  E.filename = NULL;
  E.statusmsg[0] = '\0';
  E.statusmsg_time = 0;
  E.running = true;

  if (getWindowSize(&E.screenrows, &E.screencols) == -1)
    die("getWindowSize");
  E.screenrows -= 2;
}

int edit_file(const char *s)
{
  initEditor();
  if (s)
  {
    editorOpen(s);
  }

  enableRawMode();
  editorSetStatusMessage("HELP: Ctrl-S = save | Ctrl-Q = quit | Ctrl-F = find");

  while (E.running)
  {
    editorRefreshScreen();
    editorProcessKeypress();
  }

  return 0;
}