/// @file popupmnu.c
///
/// Popup menu (PUM)
//
#include "vim.h"
#include "popupmnu.h"
#include "charset.h"
#include "ex_cmds.h"
#include "memline.h"
#include "misc2.h"
#include "move.h"
#include "option.h"
#include "screen.h"
#include "search.h"
#include "window.h"

static pumitem_T *pum_array = NULL; // items of displayed pum
static int pum_size;                // nr of items in "pum_array"
static int pum_selected;            // index of selected item or -1
static int pum_first = 0;           // index of top item

static int pum_height;              // nr of displayed pum items
static int pum_width;               // width of displayed pum items
static int pum_base_width;          // width of pum items base
static int pum_kind_width;          // width of pum items kind column
static int pum_scrollbar;           // TRUE when scrollbar present

static int pum_row;                 // top row of pum
static int pum_col;                 // left column of pum

static int pum_do_redraw = FALSE;   // do redraw anyway

static int pum_set_selected(int n, int repeat);

#define PUM_DEF_HEIGHT 10
#define PUM_DEF_WIDTH  15

/// Show the popup menu with items "array[size]".
/// "array" must remain valid until pum_undisplay() is called!
/// When possible the leftmost character is aligned with screen column "col".
/// The menu appears above the screen line "row" or at "row" + "height" - 1.
///
/// @param array
/// @param size
/// @param selected index of initially selected item, none if out of range
void pum_display(pumitem_T *array, int size, int selected)
{
  int w;
  int def_width;
  int max_width;
  int kind_width;
  int extra_width;
  int i;
  int top_clear;
  int row;
  int context_lines;
  int col;
  int above_row = cmdline_row;
  int redo_count = 0;

redo:
  def_width = PUM_DEF_WIDTH;
  max_width = 0;
  kind_width = 0;
  extra_width = 0;

  // Pretend the pum is already there to avoid that must_redraw is set when
  // 'cuc' is on.
  pum_array = (pumitem_T *)1;
  validate_cursor_col();
  pum_array = NULL;

  row = curwin->w_wrow + W_WINROW(curwin);

  if (firstwin->w_p_pvw) {
    top_clear = firstwin->w_height;
  } else {
    top_clear = 0;
  }

  // When the preview window is at the bottom stop just above it.  Also
  // avoid drawing over the status line so that it's clear there is a window
  // boundary.
  if (lastwin->w_p_pvw) {
    above_row -= lastwin->w_height + lastwin->w_status_height + 1;
  }

  // Figure out the size and position of the pum.
  if (size < PUM_DEF_HEIGHT) {
    pum_height = size;
  } else {
    pum_height = PUM_DEF_HEIGHT;
  }

  if ((p_ph > 0) && (pum_height > p_ph)) {
    pum_height = p_ph;
  }

  // Put the pum below "row" if possible.  If there are few lines decide on
  // where there is more room.
  if ((row  + 2 >= above_row - pum_height)
      && (row > (above_row - top_clear) / 2)) {
    // pum above "row"

    // Leave two lines of context if possible
    if (curwin->w_wrow - curwin->w_cline_row >= 2) {
      context_lines = 2;
    } else {
      context_lines = curwin->w_wrow - curwin->w_cline_row;
    }

    if (row >= size + context_lines) {
      pum_row = row - size - context_lines;
      pum_height = size;
    } else {
      pum_row = 0;
      pum_height = row - context_lines;
    }

    if ((p_ph > 0) && (pum_height > p_ph)) {
      pum_row += pum_height - p_ph;
      pum_height = p_ph;
    }
  } else {
    // pum below "row"

    // Leave two lines of context if possible
    if (curwin->w_cline_row + curwin->w_cline_height - curwin->w_wrow >= 3) {
      context_lines = 3;
    } else {
      context_lines = curwin->w_cline_row
                      + curwin->w_cline_height - curwin->w_wrow;
    }

    pum_row = row + context_lines;
    if (size > above_row - pum_row) {
      pum_height = above_row - pum_row;
    } else {
      pum_height = size;
    }

    if ((p_ph > 0) && (pum_height > p_ph)) {
      pum_height = p_ph;
    }
  }

  // don't display when we only have room for one line
  if ((pum_height < 1) || ((pum_height == 1) && (size > 1))) {
    return;
  }

  // If there is a preview window at the top avoid drawing over it.
  if (firstwin->w_p_pvw
      && (pum_row < firstwin->w_height)
      && (pum_height > firstwin->w_height + 4)) {
    pum_row += firstwin->w_height;
    pum_height -= firstwin->w_height;
  }

  // Compute the width of the widest match and the widest extra.
  for (i = 0; i < size; ++i) {
    w = vim_strsize(array[i].pum_text);

    if (max_width < w) {
      max_width = w;
    }

    if (array[i].pum_kind != NULL) {
      w = vim_strsize(array[i].pum_kind) + 1;

      if (kind_width < w) {
        kind_width = w;
      }
    }

    if (array[i].pum_extra != NULL) {
      w = vim_strsize(array[i].pum_extra) + 1;

      if (extra_width < w) {
        extra_width = w;
      }
    }
  }
  pum_base_width = max_width;
  pum_kind_width = kind_width;

  // Calculate column
  if (curwin->w_p_rl) {
    col = W_WINCOL(curwin) + W_WIDTH(curwin) - curwin->w_wcol - 1;
  } else {
    col = W_WINCOL(curwin) + curwin->w_wcol;
  }

  // if there are more items than room we need a scrollbar
  if (pum_height < size) {
    pum_scrollbar = 1;
    max_width++;
  } else {
    pum_scrollbar = 0;
  }

  if (def_width < max_width) {
    def_width = max_width;
  }

  if ((((col < Columns - PUM_DEF_WIDTH) || (col < Columns - max_width))
       && !curwin->w_p_rl)
      || (curwin->w_p_rl && ((col > PUM_DEF_WIDTH) || (col > max_width)))) {
    // align pum column with "col"
    pum_col = col;
    if (curwin->w_p_rl) {
      pum_width = pum_col - pum_scrollbar + 1;
    } else {
      pum_width = Columns - pum_col - pum_scrollbar;
    }

    if ((pum_width > max_width + kind_width + extra_width + 1)
        && (pum_width > PUM_DEF_WIDTH)) {
      pum_width = max_width + kind_width + extra_width + 1;

      if (pum_width < PUM_DEF_WIDTH) {
        pum_width = PUM_DEF_WIDTH;
      }
    }
  } else if (Columns < def_width) {
    // not enough room, will use what we have
    if (curwin->w_p_rl) {
      pum_col = Columns - 1;
    } else {
      pum_col = 0;
    }
    pum_width = Columns - 1;
  } else {
    if (max_width > PUM_DEF_WIDTH) {
      // truncate
      max_width = PUM_DEF_WIDTH;
    }

    if (curwin->w_p_rl) {
      pum_col = max_width - 1;
    } else {
      pum_col = Columns - max_width;
    }
    pum_width = max_width - pum_scrollbar;
  }

  pum_array = array;
  pum_size = size;

  // Set selected item and redraw.  If the window size changed need to redo
  // the positioning.  Limit this to two times, when there is not much
  // room the window size will keep changing.
  if (pum_set_selected(selected, redo_count) && (++redo_count <= 2)) {
    goto redo;
  }
}

/// Redraw the popup menu, using "pum_first" and "pum_selected".
void pum_redraw(void)
{
  int row = pum_row;
  int col;
  int attr_norm = highlight_attr[HLF_PNI];
  int attr_select = highlight_attr[HLF_PSI];
  int attr_scroll = highlight_attr[HLF_PSB];
  int attr_thumb = highlight_attr[HLF_PST];
  int attr;
  int i;
  int idx;
  char_u *s;
  char_u *p = NULL;
  int totwidth, width, w;
  int thumb_pos = 0;
  int thumb_heigth = 1;
  int round;
  int n;

  // Never display more than we have
  if (pum_first > pum_size - pum_height) {
    pum_first = pum_size - pum_height;
  }

  if (pum_scrollbar) {
    thumb_heigth = pum_height * pum_height / pum_size;
    if (thumb_heigth == 0) {
      thumb_heigth = 1;
    }
    thumb_pos = (pum_first * (pum_height - thumb_heigth)
                 + (pum_size - pum_height) / 2)
                / (pum_size - pum_height);
  }

  for (i = 0; i < pum_height; ++i) {
    idx = i + pum_first;
    attr = (idx == pum_selected) ? attr_select : attr_norm;

    // prepend a space if there is room
    if (curwin->w_p_rl) {
      if (pum_col < W_WINCOL(curwin) + W_WIDTH(curwin) - 1) {
        screen_putchar(' ', row, pum_col + 1, attr);
      }
    } else if (pum_col > 0) {
      screen_putchar(' ', row, pum_col - 1, attr);
    }

    // Display each entry, use two spaces for a Tab.
    // Do this 3 times: For the main text, kind and extra info
    col = pum_col;
    totwidth = 0;

    for (round = 1; round <= 3; ++round) {
      width = 0;
      s = NULL;

      switch (round) {
        case 1:
          p = pum_array[idx].pum_text;
          break;

        case 2:
          p = pum_array[idx].pum_kind;
          break;

        case 3:
          p = pum_array[idx].pum_extra;
          break;
      }

      if (p != NULL) {
        for (;; mb_ptr_adv(p)) {
          if (s == NULL) {
            s = p;
          }
          w = ptr2cells(p);

          if ((*p == NUL) || (*p == TAB) || (totwidth + w > pum_width)) {
            // Display the text that fits or comes before a Tab.
            // First convert it to printable characters.
            char_u *st;
            int saved = *p;

            *p = NUL;
            st = transstr(s);
            *p = saved;

            if (curwin->w_p_rl) {
              if (st != NULL) {
                char_u  *rt = reverse_text(st);

                if (rt != NULL) {
                  char_u *rt_start = rt;
                  int size;

                  size = vim_strsize(rt);

                  if (size > pum_width) {
                    do {
                      size -= has_mbyte ? (*mb_ptr2cells)(rt) : 1;
                      mb_ptr_adv(rt);
                    } while (size > pum_width);

                    if (size < pum_width) {
                      // Most left character requires 2-cells but only 1 cell
                      // is available on screen.  Put a '<' on the left of the 
                      // pum item
                      *(--rt) = '<';
                      size++;
                    }
                  }
                  screen_puts_len(rt, (int)STRLEN(rt), row, col - size + 1,
                                  attr);
                  vim_free(rt_start);
                }
                vim_free(st);
              }
              col -= width;
            } else {
              if (st != NULL) {
                screen_puts_len(st, (int)STRLEN(st), row, col, attr);
                vim_free(st);
              }
              col += width;
            }

            if (*p != TAB) {
              break;
            }

            // Display two spaces for a Tab.
            if (curwin->w_p_rl) {
              screen_puts_len((char_u *)"  ", 2, row, col - 1, attr);
              col -= 2;
            } else {
              screen_puts_len((char_u *)"  ", 2, row, col, attr);
              col += 2;
            }
            totwidth += 2;
            // start text at next char
            s = NULL;
            width = 0;
          } else {
            width += w;
          }
        }
      }

      if (round > 1) {
        n = pum_kind_width + 1;
      } else {
        n = 1;
      }

      // Stop when there is nothing more to display.
      if ((round == 3)
          || ((round == 2)
              && (pum_array[idx].pum_extra == NULL))
          || ((round == 1)
              && (pum_array[idx].pum_kind == NULL)
              && (pum_array[idx].pum_extra == NULL))
          || (pum_base_width + n >= pum_width)) {
        break;
      }

      if (curwin->w_p_rl) {
        screen_fill(row, row + 1, pum_col - pum_base_width - n + 1,
                    col + 1, ' ', ' ', attr);
        col = pum_col - pum_base_width - n + 1;
      } else {
        screen_fill(row, row + 1, col, pum_col + pum_base_width + n,
                    ' ', ' ', attr);
        col = pum_col + pum_base_width + n;
      }
      totwidth = pum_base_width + n;
    }

    if (curwin->w_p_rl) {
      screen_fill(row, row + 1, pum_col - pum_width + 1, col + 1, ' ', ' ',
                  attr);
    } else {
      screen_fill(row, row + 1, col, pum_col + pum_width, ' ', ' ', attr);
    }

    if (pum_scrollbar > 0) {
      if (curwin->w_p_rl) {
        screen_putchar(' ', row, pum_col - pum_width,
                       i >= thumb_pos && i < thumb_pos + thumb_heigth
                       ? attr_thumb : attr_scroll);
      } else {
        screen_putchar(' ', row, pum_col + pum_width,
                       i >= thumb_pos && i < thumb_pos + thumb_heigth
                       ? attr_thumb : attr_scroll);
      }
    }
    row++;
  }
}

/// Set the index of the currently selected item.  The menu will scroll when
/// necessary.  When "n" is out of range don't scroll.
/// This may be repeated when the preview window is used:
/// "repeat" == 0: open preview window normally
/// "repeat" == 1: open preview window but don't set the size
/// "repeat" == 2: don't open preview window
///
/// @param n
/// @param repeat
///
/// @returns TRUE when the window was resized and the location of the popup
/// menu must be recomputed.
static int pum_set_selected(int n, int repeat)
{
  int resized = FALSE;
  int context = pum_height / 2;

  pum_selected = n;

  if ((pum_selected >= 0) && (pum_selected < pum_size)) {
    if (pum_first > pum_selected - 4) {
      // scroll down; when we did a jump it's probably a PageUp then
      // scroll a whole page
      if (pum_first > pum_selected - 2) {
        pum_first -= pum_height - 2;
        if (pum_first < 0) {
          pum_first = 0;
        } else if (pum_first > pum_selected) {
          pum_first = pum_selected;
        }
      } else {
        pum_first = pum_selected;
      }
    } else if (pum_first < pum_selected - pum_height + 5) {
      // scroll up; when we did a jump it's probably a PageDown then
      // scroll a whole page
      if (pum_first < pum_selected - pum_height + 1 + 2) {
        pum_first += pum_height - 2;
        if (pum_first < pum_selected - pum_height + 1) {
          pum_first = pum_selected - pum_height + 1;
        }
      } else {
        pum_first = pum_selected - pum_height + 1;
      }
    }

    // Give a few lines of context when possible.
    if (context > 3) {
      context = 3;
    }

    if (pum_height > 2) {
      if (pum_first > pum_selected - context) {
        // scroll down
        pum_first = pum_selected - context;

        if (pum_first < 0) {
          pum_first = 0;
        }
      } else if (pum_first < pum_selected + context - pum_height + 1) {
        // scroll up
        pum_first = pum_selected + context - pum_height + 1;
      }
    }

    // Show extra info in the preview window if there is something and
    // 'completeopt' contains "preview".
    // Skip this when tried twice already.
    // Skip this also when there is not much room.
    // NOTE: Be very careful not to sync undo!
    if ((pum_array[pum_selected].pum_info != NULL)
        && (Rows > 10)
        && (repeat <= 1)
        && (vim_strchr(p_cot, 'p') != NULL)) {
      win_T *curwin_save = curwin;
      int res = OK;

      // Open a preview window.  3 lines by default.  Prefer
      // 'previewheight' if set and smaller.
      g_do_tagpreview = 3;

      if ((p_pvh > 0) && (p_pvh < g_do_tagpreview)) {
        g_do_tagpreview = p_pvh;
      }
      resized = prepare_tagpreview(FALSE);
      g_do_tagpreview = 0;

      if (curwin->w_p_pvw) {
        if ((curbuf->b_fname == NULL)
            && (curbuf->b_p_bt[0] == 'n')
            && (curbuf->b_p_bt[2] == 'f')
            && (curbuf->b_p_bh[0] == 'w')) {
          // Already a "wipeout" buffer, make it empty.
          while (!bufempty()) {
            ml_delete((linenr_T)1, FALSE);
          }
        } else {
          // Don't want to sync undo in the current buffer.
          no_u_sync++;
          res = do_ecmd(0, NULL, NULL, NULL, ECMD_ONE, 0, NULL);
          no_u_sync--;

          if (res == OK) {
            // Edit a new, empty buffer. Set options for a "wipeout"
            // buffer.
            set_option_value((char_u *)"swf", 0L, NULL, OPT_LOCAL);
            set_option_value((char_u *)"bt", 0L,
                             (char_u *)"nofile", OPT_LOCAL);
            set_option_value((char_u *)"bh", 0L,
                             (char_u *)"wipe", OPT_LOCAL);
            set_option_value((char_u *)"diff", 0L,
                             NULL, OPT_LOCAL);
          }
        }

        if (res == OK) {
          char_u *p, *e;
          linenr_T lnum = 0;

          for (p = pum_array[pum_selected].pum_info; *p != NUL;) {
            e = vim_strchr(p, '\n');
            if (e == NULL) {
              ml_append(lnum++, p, 0, FALSE);
              break;
            } else {
              *e = NUL;
              ml_append(lnum++, p, (int)(e - p + 1), FALSE);
              *e = '\n';
              p = e + 1;
            }
          }

          // Increase the height of the preview window to show the
          // text, but no more than 'previewheight' lines.
          if (repeat == 0) {
            if (lnum > p_pvh) {
              lnum = p_pvh;
            }

            if (curwin->w_height < lnum) {
              win_setheight((int)lnum);
              resized = TRUE;
            }
          }

          curbuf->b_changed = 0;
          curbuf->b_p_ma = FALSE;
          curwin->w_cursor.lnum = 1;
          curwin->w_cursor.col = 0;

          if ((curwin != curwin_save) && win_valid(curwin_save)) {
            // Return cursor to where we were
            validate_cursor();
            redraw_later(SOME_VALID);

            // When the preview window was resized we need to
            // update the view on the buffer.  Only go back to
            // the window when needed, otherwise it will always be
            // redraw.
            if (resized) {
              win_enter(curwin_save, TRUE);
              update_topline();
            }

            // Update the screen before drawing the popup menu.
            // Enable updating the status lines.
            pum_do_redraw = TRUE;
            update_screen(0);
            pum_do_redraw = FALSE;

            if (!resized && win_valid(curwin_save)) {
              win_enter(curwin_save, TRUE);
            }

            // May need to update the screen again when there are
            // autocommands involved.
            pum_do_redraw = TRUE;
            update_screen(0);
            pum_do_redraw = FALSE;
          }
        }
      }
    }
  }

  if (!resized) {
    pum_redraw();
  }

  return resized;
}

/// Undisplay the popup menu (later).
void pum_undisplay(void)
{
  pum_array = NULL;
  redraw_all_later(SOME_VALID);
  redraw_tabline = TRUE;
  status_redraw_all();
}

/// Clear the popup menu.  Currently only resets the offset to the first
/// displayed item.
void pum_clear(void)
{
  pum_first = 0;
}

/// Overruled when "pum_do_redraw" is set, used to redraw the status lines.
///
/// @return TRUE if the popup menu is displayed.
int pum_visible(void)
{
  return !pum_do_redraw && pum_array != NULL;
}

/// Gets the height of the menu.
///
/// @return the height of the popup menu, the number of entries visible.
/// Only valid when pum_visible() returns TRUE!
int pum_get_height(void)
{
  return pum_height;
}