#include <ctype.h>   // for iscntrl
#include <stdarg.h>  // for va_list
#include <stdio.h>   // for snprintf, vsnprintf, NULL
#include <string.h>  // for strlen
#include <time.h>    // for time
#include <unistd.h>  // for STDOUT_FILENO

#include "output.h"
#include "fn.h"      // for E, editorConfig, erow, FN_VERSION, abuf, editorH...
#include "hl.h"      // for editorSyntaxToColor
#include "row.h"     // for abAppend, abFree, editorDelRow, editorRowCxToRx


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),
            "FuNote v%s", FN_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];
      unsigned char *hl = &E.row[filerow].hl[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 (hl[j] == HL_NORMAL) {
          if (current_color != -1) {
            abAppend(ab, "\x1b[39m", 5);
            current_color = -1;
          }
          abAppend(ab, &c[j], 1);
        } else {
          int color = editorSyntaxToColor(hl[j]);
          if (color != current_color) {
            current_color = color;
            char buf[16];
            int clen = snprintf(buf, sizeof(buf), "\x1b[%dm", color);
            abAppend(ab, buf, clen);
          }
          abAppend(ab, &c[j], 1);
        }
      }
      abAppend(ab, "\x1b[39m", 5);
    }

    abAppend(ab, "\x1b[K", 3); // Erase one line
    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%s",
      E.filename ? E.filename : "[No Name]",
      E.dirty ? "*" : "");
  int rlen = snprintf(rstatus, sizeof(rstatus), "%s | %d/%d",
      E.syntax ? E.syntax->filetype : "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); // Hide cursor
  abAppend(&ab, "\x1b[H", 3); // CUP (cursor position)

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

  // Update cursor position
  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); // Show cursor

  write(STDOUT_FILENO, 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);
}


// Line oriented actions

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--;
  }
}