// This is an open source non-commercial project. Dear PVS-Studio, please check
// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com

/// @file popupmnu.c
///
/// Popup menu (PUM)

#include <assert.h>
#include <inttypes.h>
#include <stdbool.h>

#include "nvim/vim.h"
#include "nvim/api/private/helpers.h"
#include "nvim/ascii.h"
#include "nvim/popupmnu.h"
#include "nvim/charset.h"
#include "nvim/ex_cmds.h"
#include "nvim/memline.h"
#include "nvim/move.h"
#include "nvim/option.h"
#include "nvim/screen.h"
#include "nvim/search.h"
#include "nvim/strings.h"
#include "nvim/memory.h"
#include "nvim/window.h"
#include "nvim/edit.h"
#include "nvim/ui.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 bool pum_is_visible = false;
static bool pum_external = false;

#ifdef INCLUDE_GENERATED_DECLARATIONS
# include "popupmnu.c.generated.h"
#endif
#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
/// @param array_changed if true, array contains different items since last call
///                      if false, a new item is selected, but the array
///                      is the same
void pum_display(pumitem_T *array, int size, int selected, bool array_changed)
{
  int w;
  int def_width;
  int max_width;
  int kind_width;
  int extra_width;
  int i;
  int row;
  int context_lines;
  int col;
  int above_row;
  int below_row;
  int redo_count = 0;

  if (!pum_is_visible) {
    // To keep the code simple, we only allow changing the
    // draw mode when the popup menu is not being displayed
    pum_external = ui_is_external(kUIPopupmenu);
  }

  do {
    // Mark the pum as visible already here,
    // to avoid that must_redraw is set when 'cursorcolumn' is on.
    pum_is_visible = true;
    validate_cursor_col();
    above_row = 0;
    below_row = cmdline_row;

    // anchor position: the start of the completed word
    row = curwin->w_wrow + curwin->w_winrow;
    if (curwin->w_p_rl) {
      col = curwin->w_wincol + curwin->w_width - curwin->w_wcol - 1;
    } else {
      col = curwin->w_wincol + curwin->w_wcol;
    }

    if (pum_external) {
      if (array_changed) {
        Array arr = ARRAY_DICT_INIT;
        for (i = 0; i < size; i++) {
          Array item = ARRAY_DICT_INIT;
          ADD(item, STRING_OBJ(cstr_to_string((char *)array[i].pum_text)));
          ADD(item, STRING_OBJ(cstr_to_string((char *)array[i].pum_kind)));
          ADD(item, STRING_OBJ(cstr_to_string((char *)array[i].pum_extra)));
          ADD(item, STRING_OBJ(cstr_to_string((char *)array[i].pum_info)));
          ADD(arr, ARRAY_OBJ(item));
        }
        ui_call_popupmenu_show(arr, selected, row, col);
      } else {
        ui_call_popupmenu_select(selected);
      }
      return;
    }

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

    win_T *pvwin = NULL;
    FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
      if (wp->w_p_pvw) {
        pvwin = wp;
        break;
      }
    }

    if (pvwin != NULL) {
      if (pvwin->w_winrow < curwin->w_winrow) {
        above_row = pvwin->w_winrow + pvwin->w_height;
      } else if (pvwin->w_winrow > curwin->w_winrow + curwin->w_height) {
        below_row = pvwin->w_winrow;
      }
    }

    // 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 = (int)p_ph;
    }

    // Put the pum below "row" if possible.  If there are few lines decide on
    // where there is more room.
    if (row + 2 >= below_row - pum_height
        && row - above_row > (below_row - above_row) / 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 - (int)p_ph;
        pum_height = (int)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 > below_row - pum_row) {
        pum_height = below_row - pum_row;
      } else {
        pum_height = size;
      }

      if ((p_ph > 0) && (pum_height > p_ph)) {
        pum_height = (int)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 above, avoid drawing over it.
    // Do keep at least 10 entries.
    if (pvwin != NULL && pum_row < above_row && pum_height > 10) {
      if (row - above_row < 10) {
        pum_row = row - 10;
        pum_height = 10;
      } else {
        pum_row = above_row;
        pum_height = row - above_row;
      }
    }

    // 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;

    // 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 {
        assert(Columns - pum_col - pum_scrollbar >= INT_MIN
               && Columns - pum_col - pum_scrollbar <= INT_MAX);
        pum_width = (int)(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) {
        assert(Columns - 1 >= INT_MIN);
        pum_col = (int)(Columns - 1);
      } else {
        pum_col = 0;
      }
      assert(Columns - 1 >= INT_MIN);
      pum_width = (int)(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 {
        assert(Columns - max_width >= INT_MIN
               && Columns - max_width <= INT_MAX);
        pum_col = (int)(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.
  } while (pum_set_selected(selected, redo_count) && (++redo_count <= 2));
}

/// Redraw the popup menu, using "pum_first" and "pum_selected".
void pum_redraw(void)
{
  int row = pum_row;
  int col;
  int attr_norm = win_hl_attr(curwin, HLF_PNI);
  int attr_select = win_hl_attr(curwin, HLF_PSI);
  int attr_scroll = win_hl_attr(curwin, HLF_PSB);
  int attr_thumb = win_hl_attr(curwin, 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;

    screen_puts_line_start(row);

    // prepend a space if there is room
    if (curwin->w_p_rl) {
      if (pum_col < curwin->w_wincol + curwin->w_width - 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;
            char_u saved = *p;

            *p = NUL;
            st = (char_u *)transstr((const char *)s);
            *p = saved;

            if (curwin->w_p_rl) {
              char_u *rt = reverse_text(st);
              char_u *rt_start = rt;
              int size = vim_strsize(rt);

              if (size > pum_width) {
                do {
                  size -= utf_ptr2cells(rt);
                  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);
              xfree(rt_start);
              xfree(st);
              col -= width;
            } else {
              screen_puts_len(st, (int)STRLEN(st), row, col, attr);
              xfree(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);
      }
    }
    screen_puts_line_flush(false);
    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;
      tabpage_T *curtab_save = curtab;
      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 = (int)p_pvh;
      }
      RedrawingDisabled++;
      // Prevent undo sync here, if an autocommand syncs undo weird
      // things can happen to the undo tree.
      no_u_sync++;
      resized = prepare_tagpreview(false);
      no_u_sync--;
      RedrawingDisabled--;
      g_do_tagpreview = 0;

      if (curwin->w_p_pvw) {
        if (!resized
            && (curbuf->b_nwindows == 1)
            && (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("swf", 0L, NULL, OPT_LOCAL);
            set_option_value("bt", 0L, "nofile", OPT_LOCAL);
            set_option_value("bh", 0L, "wipe", OPT_LOCAL);
            set_option_value("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 = false;
          curbuf->b_p_ma = FALSE;
          curwin->w_cursor.lnum = 1;
          curwin->w_cursor.col = 0;

          if ((curwin != curwin_save && win_valid(curwin_save))
              || (curtab != curtab_save && valid_tabpage(curtab_save))) {
            if (curtab != curtab_save && valid_tabpage(curtab_save)) {
              goto_tabpage_tp(curtab_save, false, false);
            }

            // When the first completion is done and the preview
            // window is not resized, skip the preview window's
            // status line redrawing.
            if (ins_compl_active() && !resized) {
              curwin->w_redr_status = FALSE;
            }

            // 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) {
              no_u_sync++;
              win_enter(curwin_save, true);
              no_u_sync--;
              update_topline();
            }

            // Update the screen before drawing the popup menu.
            // Enable updating the status lines.
            pum_is_visible = false;
            update_screen(0);
            pum_is_visible = true;

            if (!resized && win_valid(curwin_save)) {
              no_u_sync++;
              win_enter(curwin_save, true);
              no_u_sync--;
            }

            // May need to update the screen again when there are
            // autocommands involved.
            pum_is_visible = false;
            update_screen(0);
            pum_is_visible = true;
          }
        }
      }
    }
  }

  if (!resized) {
    pum_redraw();
  }

  return resized;
}

/// Undisplay the popup menu (later).
void pum_undisplay(void)
{
  pum_is_visible = false;
  pum_array = NULL;

  if (pum_external) {
    ui_call_popupmenu_hide();
  } else {
    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;
}

/// @return true if the popup menu is displayed.
bool pum_visible(void)
{
  return pum_is_visible;
}

/// @return true if the popup menu is displayed and drawn on the grid.
bool pum_drawn(void)
{
  return pum_visible() && !pum_external;
}

/// 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;
}