#include "edit.h"
#include "arena_alloc.h"
#include "gapbuffer.h"
#include "mprintf.h"
#include "self.h"
#include "walloc.h"
#include <arena.h>
#include <kb.h>
#include <liballoc.h>
#include <list.h>
#include <printf.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <system.h>
#include <tcursor.h>
#include <terminal.h>
#include <tgraphics.h>
#include <tscreen.h>

struct edit_line {
  struct list_node_link lines_link;
  struct gapbuffer gb;
};

struct cursor {
  size_t col;
  size_t line;
};

struct editor {
  struct list_node_link* lines;
  struct edit_line* current_line;
  struct cursor cursor;
  size_t col_offset;
  size_t row_offset;
};

static struct editor editor;

static bool prepare_lines_cb (void* ctx, const char* start, size_t len) {
  struct edit_line* line = malloc (sizeof (*line));

  if (line == NULL)
    return false;

  memset (line, 0, sizeof (*line));
  gapbuffer_init (&wmalloc, NULL, &line->gb, len);

  for (size_t chr = 0; chr < len; chr++)
    gapbuffer_insert (&wrealloc, NULL, &line->gb, start[chr]);

  list_append (editor.lines, &line->lines_link);

  if (editor.current_line == NULL)
    editor.current_line = line;

  return true;
}

static void prepare_lines (const char* text) { strtokenize (text, '\n', NULL, &prepare_lines_cb); }

static void update_horz_scroll (size_t screen_cols) {
  if (editor.cursor.col < editor.col_offset)
    editor.col_offset = editor.cursor.col;

  if (editor.cursor.col >= editor.col_offset + screen_cols)
    editor.col_offset = editor.cursor.col - screen_cols + 1;
}

static void update_vert_scroll (size_t screen_rows) {
  if (editor.cursor.line < editor.row_offset)
    editor.row_offset = editor.cursor.line;

  if (editor.cursor.line >= editor.row_offset + (screen_rows - 1))
    editor.row_offset = editor.cursor.line - (screen_rows - 1) + 1;
}

void edit_start (const char* file_path, const char* text) {
  prepare_lines (text);
  struct arena temp_arena;
  memset (&temp_arena, 0, sizeof (temp_arena));
  size_t cols, rows;

  terminal_dimensions (&cols, &rows);

  mprintf (ANSIQ_SCR_CLR_ALL ANSIQ_CUR_INVISIBLE);

  bool edit_run = true;

  while (edit_run) {
    update_horz_scroll (cols);
    update_vert_scroll (rows);

    int w;
    const size_t backbuffer_max = 128 * 1024;
    size_t bb_remaining = backbuffer_max;
    char* backbuffer = arena_malloc (&temp_arena, backbuffer_max);
    memset (backbuffer, 0, backbuffer_max);
    char* bbptr = backbuffer;

    w = snprintf (bbptr, bb_remaining, ANSIQ_CUR_HOME);
    bbptr += w;
    bb_remaining -= w;

    size_t lines_drawn = 0;
    size_t current_idx = 0;

    struct list_node_link *line_link, *tmp_line_link;
    list_foreach (editor.lines, line_link, tmp_line_link) {
      if (current_idx < editor.row_offset) {
        current_idx++;
        continue;
      }

      if (lines_drawn >= rows - 1)
        break;

      struct edit_line* line = list_entry (line_link, struct edit_line, lines_link);

      w = snprintf (bbptr, bb_remaining, ANSIQ_SCR_CLR_LINE);
      bbptr += w;
      bb_remaining -= w;

      char* render = gapbuffer_get_string (&warena_malloc, &temp_arena, &line->gb);
      size_t len = strlen (render);

      if (len > editor.col_offset) {
        char* visible = render + editor.col_offset;
        size_t visible_len = len - editor.col_offset;

        if (visible_len > cols)
          visible_len = cols;

        w = snprintf (bbptr, bb_remaining, "%.*s", (int)visible_len, visible);
        bbptr += w;
        bb_remaining -= w;
      }

      w = snprintf (bbptr, bb_remaining, ANSIQ_SCR_CLR2END "\n");
      bbptr += w;
      bb_remaining -= w;

      lines_drawn++;
      current_idx++;
    }

    w = snprintf (bbptr, bb_remaining, ANSIQ_DYN_CUR_SET ANSIQ_SCR_CLR_LINE, (int)rows, 1);
    bbptr += w;
    bb_remaining -= w;

    w = snprintf (bbptr, bb_remaining, "Editing %s; line %zu col %zu", file_path,
                  editor.cursor.line, editor.cursor.col);
    bbptr += w;
    bb_remaining -= w;

    w = snprintf (bbptr, bb_remaining, ANSIQ_DYN_CUR_SET ANSIQ_CUR_VISIBLE,
                  (int)(editor.cursor.line - editor.row_offset) + 1,
                  (int)(editor.cursor.col - editor.col_offset) + 1);
    bbptr += w;
    bb_remaining -= w;

    mail_send (e_pgid, backbuffer, strlen (backbuffer));

    uint8_t ch = 0;
    mail_receive (&ch, 1);

    gapbuffer_move (&editor.current_line->gb, editor.cursor.col);

    switch (ch) {
    case '\b':
      if (editor.cursor.col > 0) {
        editor.cursor.col--;
        gapbuffer_backspace (&editor.current_line->gb);
      }
      break;
    case KB_DELETE:
      if (editor.cursor.col < gapbuffer_length (&editor.current_line->gb))
        editor.current_line->gb.gap_end++;
      break;
    case KB_LEFT:
      if (editor.cursor.col > 0)
        editor.cursor.col--;
      break;
    case KB_RIGHT:
      if (editor.cursor.col < gapbuffer_length (&editor.current_line->gb))
        editor.cursor.col++;
      break;
    case KB_UP: {
      if (editor.cursor.line > 0) {
        editor.cursor.line--;
        editor.current_line =
            list_entry (editor.current_line->lines_link.prev, struct edit_line, lines_link);
        size_t len = gapbuffer_length (&editor.current_line->gb);
        if (editor.cursor.col > len)
          editor.cursor.col = len;
      }
    } break;
    case KB_DOWN: {
      if (editor.current_line->lines_link.next != NULL) {
        editor.cursor.line++;
        editor.current_line =
            list_entry (editor.current_line->lines_link.next, struct edit_line, lines_link);
        size_t len = gapbuffer_length (&editor.current_line->gb);
        if (editor.cursor.col > len)
          editor.cursor.col = len;
      }
    } break;
    case KB_HOME:
      editor.cursor.col = 0;
      break;
    case KB_END:
      editor.cursor.col = gapbuffer_length (&editor.current_line->gb);
      break;
    case KB_CTRL ('Q'):
      edit_run = false;
      break;
    default:
      if (isprint (ch)) {
        gapbuffer_insert (&wrealloc, NULL, &editor.current_line->gb, ch);
        editor.cursor.col++;
      }
      break;
    }

    arena_reset (&temp_arena);
  }

  mprintf (ANSIQ_SCR_CLR_ALL ANSIQ_CUR_VISIBLE);

  arena_destroy (&temp_arena);

  struct list_node_link *line_link, *tmp_line_link;
  list_foreach (editor.lines, line_link, tmp_line_link) {
    struct edit_line* line = list_entry (line_link, struct edit_line, lines_link);
    free (line->gb.buffer);
    free (line);
  }

  memset (&editor, 0, sizeof (editor));
}