/**
 * @file
 * Sidebar observers
 *
 * @authors
 * Copyright (C) 2019-2023 Richard Russon <rich@flatcap.org>
 * Copyright (C) 2021 Ashish Panigrahi <ashish.panigrahi@protonmail.com>
 * Copyright (C) 2022 Pietro Cerutti <gahr@gahr.ch>
 *
 * @copyright
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * @page sidebar_observers Sidebar observers
 *
 * Sidebar observers
 */

#include "config.h"
#include <stdbool.h>
#include <stddef.h>
#include "private.h"
#include "mutt/lib.h"
#include "config/lib.h"
#include "core/lib.h"
#include "gui/lib.h"
#include "color/lib.h"
#include "index/lib.h"

void sb_win_remove_observers(struct MuttWindow *win);

/**
 * calc_divider - Decide what actions are required for the divider
 * @param wdata   Sidebar data
 * @retval true The width has changed
 *
 * If the divider changes width, then Window will need to be reflowed.
 */
static bool calc_divider(struct SidebarWindowData *wdata)
{
  enum DivType type = SB_DIV_USER;
  bool changed = false;
  const char *const c_sidebar_divider_char = cs_subset_string(NeoMutt->sub, "sidebar_divider_char");

  // Calculate the width of the delimiter in screen cells
  int width = mutt_strwidth(c_sidebar_divider_char);
  if (width < 1)
  {
    type = SB_DIV_ASCII;
    goto done;
  }

  const bool c_ascii_chars = cs_subset_bool(NeoMutt->sub, "ascii_chars");
  if (c_ascii_chars || !CharsetIsUtf8)
  {
    const size_t len = mutt_str_len(c_sidebar_divider_char);
    for (size_t i = 0; i < len; i++)
    {
      if (c_sidebar_divider_char[i] & ~0x7F) // high-bit is set
      {
        type = SB_DIV_ASCII;
        width = 1;
        break;
      }
    }
  }

done:
  changed = (width != wdata->divider_width);

  wdata->divider_type = type;
  wdata->divider_width = width;

  return changed;
}

/**
 * sb_win_init - Initialise and insert the Sidebar Window
 * @param dlg Index Dialog
 * @retval ptr Sidebar Window
 */
static struct MuttWindow *sb_win_init(struct MuttWindow *dlg)
{
  dlg->orient = MUTT_WIN_ORIENT_HORIZONTAL;

  struct MuttWindow *index_panel = TAILQ_FIRST(&dlg->children);
  mutt_window_remove_child(dlg, index_panel);

  struct MuttWindow *pager_panel = TAILQ_FIRST(&dlg->children);
  mutt_window_remove_child(dlg, pager_panel);

  struct MuttWindow *cont_right = mutt_window_new(WT_CONTAINER, MUTT_WIN_ORIENT_VERTICAL,
                                                  MUTT_WIN_SIZE_MAXIMISE, MUTT_WIN_SIZE_UNLIMITED,
                                                  MUTT_WIN_SIZE_UNLIMITED);
  dlg->focus = cont_right;

  mutt_window_add_child(cont_right, index_panel);
  mutt_window_add_child(cont_right, pager_panel);
  cont_right->focus = index_panel;

  const short c_sidebar_width = cs_subset_number(NeoMutt->sub, "sidebar_width");
  struct MuttWindow *win_sidebar = mutt_window_new(WT_SIDEBAR, MUTT_WIN_ORIENT_HORIZONTAL,
                                                   MUTT_WIN_SIZE_FIXED, c_sidebar_width,
                                                   MUTT_WIN_SIZE_UNLIMITED);
  const bool c_sidebar_visible = cs_subset_bool(NeoMutt->sub, "sidebar_visible");
  win_sidebar->state.visible = c_sidebar_visible && (c_sidebar_width > 0);

  struct IndexSharedData *shared = dlg->wdata;
  win_sidebar->wdata = sb_wdata_new(win_sidebar, shared);
  win_sidebar->wdata_free = sb_wdata_free;

  calc_divider(win_sidebar->wdata);

  win_sidebar->recalc = sb_recalc;
  win_sidebar->repaint = sb_repaint;

  const bool c_sidebar_on_right = cs_subset_bool(NeoMutt->sub, "sidebar_on_right");
  if (c_sidebar_on_right)
  {
    mutt_window_add_child(dlg, cont_right);
    mutt_window_add_child(dlg, win_sidebar);
  }
  else
  {
    mutt_window_add_child(dlg, win_sidebar);
    mutt_window_add_child(dlg, cont_right);
  }

  sb_win_add_observers(win_sidebar);

  return win_sidebar;
}

/**
 * sb_init_data - Initialise the Sidebar data
 * @param win Sidebar Window
 */
static void sb_init_data(struct MuttWindow *win)
{
  struct SidebarWindowData *wdata = sb_wdata_get(win);
  if (!wdata)
    return;

  if (!ARRAY_EMPTY(&wdata->entries))
    return;

  struct MailboxArray ma = neomutt_mailboxes_get(NeoMutt, MUTT_MAILBOX_ANY);
  struct Mailbox **mp = NULL;
  ARRAY_FOREACH(mp, &ma)
  {
    struct Mailbox *m = *mp;

    if (m->visible)
      sb_add_mailbox(wdata, m);
  }
  ARRAY_FREE(&ma); // Clean up the ARRAY, but not the Mailboxes
}

/**
 * sb_account_observer - Notification that an Account has changed - Implements ::observer_t - @ingroup observer_api
 */
static int sb_account_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_ACCOUNT)
    return 0;
  if (!nc->global_data || !nc->event_data)
    return -1;
  if (nc->event_subtype == NT_ACCOUNT_DELETE)
    return 0;

  struct MuttWindow *win = nc->global_data;
  struct SidebarWindowData *wdata = sb_wdata_get(win);
  struct EventAccount *ev_a = nc->event_data;

  struct Mailbox **mp = NULL;
  ARRAY_FOREACH(mp, &ev_a->account->mailboxes)
  {
    sb_add_mailbox(wdata, *mp);
  }

  win->actions |= WA_RECALC;
  mutt_debug(LL_DEBUG5, "account done, request WA_RECALC\n");
  return 0;
}

/**
 * sb_color_observer - Notification that a Color has changed - Implements ::observer_t - @ingroup observer_api
 */
static int sb_color_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_COLOR)
    return 0;
  if (!nc->global_data || !nc->event_data)
    return -1;

  struct EventColor *ev_c = nc->event_data;
  struct MuttWindow *win = nc->global_data;

  enum ColorId cid = ev_c->cid;

  if (cid == MT_COLOR_MAX) // Sent on `uncolor *`
  {
    // Set a default style
    struct AttrColor *ac = simple_color_get(MT_COLOR_SIDEBAR_HIGHLIGHT);
    ac->attrs = A_UNDERLINE;
  }

  switch (cid)
  {
    case MT_COLOR_INDICATOR:
    case MT_COLOR_NORMAL:
    case MT_COLOR_SIDEBAR_BACKGROUND:
    case MT_COLOR_SIDEBAR_DIVIDER:
    case MT_COLOR_SIDEBAR_FLAGGED:
    case MT_COLOR_SIDEBAR_HIGHLIGHT:
    case MT_COLOR_SIDEBAR_INDICATOR:
    case MT_COLOR_SIDEBAR_NEW:
    case MT_COLOR_SIDEBAR_ORDINARY:
    case MT_COLOR_SIDEBAR_SPOOLFILE:
    case MT_COLOR_SIDEBAR_UNREAD:
    case MT_COLOR_MAX: // Sent on `uncolor *`
      win->actions |= WA_REPAINT;
      mutt_debug(LL_DEBUG5, "color done, request WA_REPAINT\n");
      break;

    default:
      break;
  }
  return 0;
}

/**
 * sb_command_observer - Notification that a Command has occurred - Implements ::observer_t - @ingroup observer_api
 */
static int sb_command_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_COMMAND)
    return 0;
  if (!nc->global_data || !nc->event_data)
    return -1;

  struct Command *cmd = nc->event_data;

  if ((cmd->parse != sb_parse_sidebar_pin) && (cmd->parse != sb_parse_sidebar_unpin))
    return 0;

  struct MuttWindow *win = nc->global_data;
  win->actions |= WA_RECALC;
  mutt_debug(LL_DEBUG5, "command done, request WA_RECALC\n");
  return 0;
}

/**
 * sb_config_observer - Notification that a Config Variable has changed - Implements ::observer_t - @ingroup observer_api
 */
static int sb_config_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_CONFIG)
    return 0;
  if (!nc->global_data || !nc->event_data)
    return -1;

  struct EventConfig *ev_c = nc->event_data;

  if (!mutt_strn_equal(ev_c->name, "sidebar_", 8) &&
      !mutt_str_equal(ev_c->name, "ascii_chars") &&
      !mutt_str_equal(ev_c->name, "folder") && !mutt_str_equal(ev_c->name, "spool_file"))
  {
    return 0;
  }

  if (mutt_str_equal(ev_c->name, "sidebar_next_new_wrap"))
    return 0; // Affects the behaviour, but not the display

  mutt_debug(LL_DEBUG5, "config: %s\n", ev_c->name);

  struct MuttWindow *win = nc->global_data;

  if (mutt_str_equal(ev_c->name, "sidebar_visible"))
  {
    const bool c_sidebar_visible = cs_subset_bool(NeoMutt->sub, "sidebar_visible");
    window_set_visible(win, c_sidebar_visible);
    window_reflow(win->parent);
    mutt_debug(LL_DEBUG5, "config done, request WA_REFLOW\n");
    return 0;
  }

  if (mutt_str_equal(ev_c->name, "sidebar_width"))
  {
    const short c_sidebar_width = cs_subset_number(NeoMutt->sub, "sidebar_width");
    win->req_cols = c_sidebar_width;
    window_reflow(win->parent);
    mutt_debug(LL_DEBUG5, "config done, request WA_REFLOW\n");
    return 0;
  }

  if (mutt_str_equal(ev_c->name, "spool_file"))
  {
    win->actions |= WA_REPAINT;
    mutt_debug(LL_DEBUG5, "config done, request WA_REPAINT\n");
    return 0;
  }

  if (mutt_str_equal(ev_c->name, "sidebar_on_right"))
  {
    struct MuttWindow *parent = win->parent;
    struct MuttWindow *first = TAILQ_FIRST(&parent->children);
    const bool c_sidebar_on_right = cs_subset_bool(NeoMutt->sub, "sidebar_on_right");

    if ((c_sidebar_on_right && (first == win)) || (!c_sidebar_on_right && (first != win)))
    {
      // Swap the Sidebar and the Container of the Index/Pager
      TAILQ_REMOVE(&parent->children, first, entries);
      TAILQ_INSERT_TAIL(&parent->children, first, entries);
    }

    window_reflow(win->parent);
    mutt_debug(LL_DEBUG5, "config done, request WA_REFLOW\n");
    return 0;
  }

  if (mutt_str_equal(ev_c->name, "ascii_chars") ||
      mutt_str_equal(ev_c->name, "sidebar_divider_char"))
  {
    struct SidebarWindowData *wdata = sb_wdata_get(win);
    calc_divider(wdata);
    win->actions |= WA_RECALC;
    mutt_debug(LL_DEBUG5, "config done, request WA_RECALC\n");
    return 0;
  }

  // All the remaining config changes...
  win->actions |= WA_RECALC;
  mutt_debug(LL_DEBUG5, "config done, request WA_RECALC\n");
  return 0;
}

/**
 * sb_index_observer - Notification that the Index has changed - Implements ::observer_t - @ingroup observer_api
 */
static int sb_index_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_INDEX)
    return 0;
  if (!nc->global_data || !nc->event_data)
    return 0;
  if (!(nc->event_subtype & NT_INDEX_MAILBOX))
    return 0;

  struct MuttWindow *win_sidebar = nc->global_data;
  struct IndexSharedData *shared = nc->event_data;

  struct SidebarWindowData *wdata = sb_wdata_get(win_sidebar);
  sb_set_current_mailbox(wdata, shared->mailbox);

  win_sidebar->actions |= WA_RECALC;
  mutt_debug(LL_DEBUG5, "index done, request WA_RECALC\n");

  return 0;
}

/**
 * sb_mailbox_observer - Notification that a Mailbox has changed - Implements ::observer_t - @ingroup observer_api
 */
static int sb_mailbox_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_MAILBOX)
    return 0;
  if (!nc->global_data || !nc->event_data)
    return -1;

  struct MuttWindow *win = nc->global_data;

  struct SidebarWindowData *wdata = sb_wdata_get(win);
  struct EventMailbox *ev_m = nc->event_data;

  if (nc->event_subtype == NT_MAILBOX_ADD)
  {
    sb_add_mailbox(wdata, ev_m->mailbox);
  }
  else if (nc->event_subtype == NT_MAILBOX_DELETE)
  {
    sb_remove_mailbox(wdata, ev_m->mailbox);
  }

  win->actions |= WA_RECALC;
  mutt_debug(LL_DEBUG5, "mailbox done, request WA_RECALC\n");
  return 0;
}

/**
 * sb_window_observer - Notification that a Window has changed - Implements ::observer_t - @ingroup observer_api
 */
static int sb_window_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_WINDOW)
    return 0;
  if (!nc->global_data || !nc->event_data)
    return -1;

  struct MuttWindow *win = nc->global_data;
  struct EventWindow *ev_w = nc->event_data;
  if (ev_w->win != win)
    return 0;

  if (nc->event_subtype == NT_WINDOW_STATE)
  {
    win->actions |= WA_RECALC;
    mutt_debug(LL_DEBUG5, "window state done, request WA_RECALC\n");
  }
  else if (nc->event_subtype == NT_WINDOW_DELETE)
  {
    mutt_debug(LL_DEBUG5, "window delete done\n");
    sb_win_remove_observers(win);
  }
  return 0;
}

/**
 * sb_win_add_observers - Add Observers to the Sidebar Window
 * @param win Sidebar Window
 */
void sb_win_add_observers(struct MuttWindow *win)
{
  if (!win || !NeoMutt)
    return;

  struct MuttWindow *dlg = window_find_parent(win, WT_DLG_INDEX);

  mutt_color_observer_add(sb_color_observer, win);
  notify_observer_add(NeoMutt->notify, NT_ACCOUNT, sb_account_observer, win);
  notify_observer_add(NeoMutt->notify, NT_COMMAND, sb_command_observer, win);
  notify_observer_add(NeoMutt->sub->notify, NT_CONFIG, sb_config_observer, win);
  notify_observer_add(dlg->notify, NT_INDEX, sb_index_observer, win);
  notify_observer_add(NeoMutt->notify, NT_MAILBOX, sb_mailbox_observer, win);
  notify_observer_add(win->notify, NT_WINDOW, sb_window_observer, win);
}

/**
 * sb_win_remove_observers - Remove Observers from the Sidebar Window
 * @param win Sidebar Window
 */
void sb_win_remove_observers(struct MuttWindow *win)
{
  if (!win || !NeoMutt)
    return;

  struct MuttWindow *dlg = window_find_parent(win, WT_DLG_INDEX);

  mutt_color_observer_remove(sb_color_observer, win);
  notify_observer_remove(NeoMutt->notify, sb_account_observer, win);
  notify_observer_remove(NeoMutt->notify, sb_command_observer, win);
  notify_observer_remove(NeoMutt->sub->notify, sb_config_observer, win);
  notify_observer_remove(dlg->notify, sb_index_observer, win);
  notify_observer_remove(NeoMutt->notify, sb_mailbox_observer, win);
  notify_observer_remove(win->notify, sb_window_observer, win);
}

/**
 * sb_insertion_window_observer - Notification that a Window has changed - Implements ::observer_t - @ingroup observer_api
 */
int sb_insertion_window_observer(struct NotifyCallback *nc)
{
  if (nc->event_type != NT_WINDOW)
    return 0;
  if (!nc->event_data)
    return -1;
  if (nc->event_subtype != NT_WINDOW_DIALOG)
    return 0;

  struct EventWindow *ev_w = nc->event_data;
  if (ev_w->win->type != WT_DLG_INDEX)
    return 0;

  if (ev_w->flags & WN_VISIBLE)
  {
    mutt_debug(LL_DEBUG5, "insertion: visible\n");
    struct MuttWindow *win_sidebar = sb_win_init(ev_w->win);
    sb_init_data(win_sidebar);
  }
  else if (ev_w->flags & WN_HIDDEN)
  {
    mutt_debug(LL_DEBUG5, "insertion: hidden\n");
    sb_win_remove_observers(ev_w->win);
  }

  return 0;
}
