--- ### AstroNvim Buffer Utilities
--
-- Buffer management related utility functions
--
-- This module can be loaded with `local buffer_utils = require "astronvim.utils.buffer"`
--
-- @module astronvim.utils.buffer
-- @copyright 2022
-- @license GNU General Public License v3.0

local M = {}

local utils = require "astronvim.utils"

--- Placeholders for keeping track of most recent and previous buffer
M.current_buf, M.last_buf = nil, nil

-- TODO: Add user configuration table for this once resession is default
--- Configuration table for controlling session options
M.sessions = {
  autosave = {
    last = true, -- auto save last session
    cwd = true, -- auto save session for each working directory
  },
  ignore = {
    dirs = {}, -- working directories to ignore sessions in
    filetypes = { "gitcommit", "gitrebase" }, -- filetypes to ignore sessions
    buftypes = {}, -- buffer types to ignore sessions
  },
}

--- Check if a buffer is valid
---@param bufnr number? The buffer to check, default to current buffer
---@return boolean # Whether the buffer is valid or not
function M.is_valid(bufnr)
  if not bufnr then bufnr = 0 end
  return vim.api.nvim_buf_is_valid(bufnr) and vim.bo[bufnr].buflisted
end

--- Check if a buffer can be restored
---@param bufnr number The buffer to check
---@return boolean # Whether the buffer is restorable or not
function M.is_restorable(bufnr)
  if not M.is_valid(bufnr) or vim.api.nvim_get_option_value("bufhidden", { buf = bufnr }) ~= "" then return false end

  local buftype = vim.api.nvim_get_option_value("buftype", { buf = bufnr })
  if buftype == "" then
    -- Normal buffer, check if it listed.
    if not vim.api.nvim_get_option_value("buflisted", { buf = bufnr }) then return false end
    -- Check if it has a filename.
    if vim.api.nvim_buf_get_name(bufnr) == "" then return false end
  end

  if
    vim.tbl_contains(M.sessions.ignore.filetypes, vim.api.nvim_get_option_value("filetype", { buf = bufnr }))
    or vim.tbl_contains(M.sessions.ignore.buftypes, vim.api.nvim_get_option_value("buftype", { buf = bufnr }))
  then
    return false
  end
  return true
end

--- Check if the current buffers form a valid session
---@return boolean # Whether the current session of buffers is a valid session
function M.is_valid_session()
  local cwd = vim.fn.getcwd()
  for _, dir in ipairs(M.sessions.ignore.dirs) do
    if vim.fn.expand(dir) == cwd then return false end
  end
  for _, bufnr in ipairs(vim.api.nvim_list_bufs()) do
    if M.is_restorable(bufnr) then return true end
  end
  return false
end

--- Move the current buffer tab n places in the bufferline
---@param n number The number of tabs to move the current buffer over by (positive = right, negative = left)
function M.move(n)
  if n == 0 then return end -- if n = 0 then no shifts are needed
  local bufs = vim.t.bufs -- make temp variable
  for i, bufnr in ipairs(bufs) do -- loop to find current buffer
    if bufnr == vim.api.nvim_get_current_buf() then -- found index of current buffer
      for _ = 0, (n % #bufs) - 1 do -- calculate number of right shifts
        local new_i = i + 1 -- get next i
        if i == #bufs then -- if at end, cycle to beginning
          new_i = 1 -- next i is actually 1 if at the end
          local val = bufs[i] -- save value
          table.remove(bufs, i) -- remove from end
          table.insert(bufs, new_i, val) -- insert at beginning
        else -- if not at the end,then just do an in place swap
          bufs[i], bufs[new_i] = bufs[new_i], bufs[i]
        end
        i = new_i -- iterate i to next value
      end
      break
    end
  end
  vim.t.bufs = bufs -- set buffers
  utils.event "BufsUpdated"
  vim.cmd.redrawtabline() -- redraw tabline
end

--- Navigate left and right by n places in the bufferline
-- @param n number The number of tabs to navigate to (positive = right, negative = left)
function M.nav(n)
  local current = vim.api.nvim_get_current_buf()
  for i, v in ipairs(vim.t.bufs) do
    if current == v then
      vim.cmd.b(vim.t.bufs[(i + n - 1) % #vim.t.bufs + 1])
      break
    end
  end
end

--- Navigate to a specific buffer by its position in the bufferline
---@param tabnr number The position of the buffer to navigate to
function M.nav_to(tabnr) vim.cmd.b(vim.t.bufs[tabnr]) end

--- Navigate to the previously used buffer
function M.prev()
  if vim.fn.bufnr() == M.current_buf then
    if M.last_buf then
      vim.cmd.b(M.last_buf)
    else
      utils.notify "No previous buffer found"
    end
  else
    utils.notify "Must be in a main editor window to switch the window buffer"
  end
end

--- Close a given buffer
---@param bufnr? number The buffer to close or the current buffer if not provided
---@param force? boolean Whether or not to foce close the buffers or confirm changes (default: false)
function M.close(bufnr, force)
  if utils.is_available "mini.bufremove" and M.is_valid(bufnr) and #vim.t.bufs > 1 then
    if not force and vim.api.nvim_get_option_value("modified", { buf = bufnr }) then
      local bufname = vim.fn.expand "%"
      local empty = bufname == ""
      if empty then bufname = "Untitled" end
      local confirm = vim.fn.confirm(('Save changes to "%s"?'):format(bufname), "&Yes\n&No\n&Cancel", 1, "Question")
      if confirm == 1 then
        if empty then return end
        vim.cmd.write()
      elseif confirm == 2 then
        force = true
      else
        return
      end
    end
    require("mini.bufremove").delete(bufnr, force)
  else
    vim.cmd((force and "bd!" or "confirm bd") .. (bufnr == nil and "" or bufnr))
  end
end

--- Close all buffers
---@param keep_current? boolean Whether or not to keep the current buffer (default: false)
---@param force? boolean Whether or not to foce close the buffers or confirm changes (default: false)
function M.close_all(keep_current, force)
  if keep_current == nil then keep_current = false end
  local current = vim.api.nvim_get_current_buf()
  for _, bufnr in ipairs(vim.t.bufs) do
    if not keep_current or bufnr ~= current then M.close(bufnr, force) end
  end
end

--- Close buffers to the left of the current buffer
---@param force? boolean Whether or not to foce close the buffers or confirm changes (default: false)
function M.close_left(force)
  local current = vim.api.nvim_get_current_buf()
  for _, bufnr in ipairs(vim.t.bufs) do
    if bufnr == current then break end
    M.close(bufnr, force)
  end
end

--- Close buffers to the right of the current buffer
---@param force? boolean Whether or not to foce close the buffers or confirm changes (default: false)
function M.close_right(force)
  local current = vim.api.nvim_get_current_buf()
  local after_current = false
  for _, bufnr in ipairs(vim.t.bufs) do
    if after_current then M.close(bufnr, force) end
    if bufnr == current then after_current = true end
  end
end

--- Sort a the buffers in the current tab based on some comparator
---@param compare_func string|function a string of a comparator defined in require("astronvim.utils.buffer").comparator or a custom comparator function
---@param skip_autocmd boolean|nil whether or not to skip triggering AstroBufsUpdated autocmd event
---@return boolean # Whether or not the buffers were sorted
function M.sort(compare_func, skip_autocmd)
  if type(compare_func) == "string" then compare_func = M.comparator[compare_func] end
  if type(compare_func) == "function" then
    local bufs = vim.t.bufs
    table.sort(bufs, compare_func)
    vim.t.bufs = bufs
    if not skip_autocmd then utils.event "BufsUpdated" end
    vim.cmd.redrawtabline()
    return true
  end
  return false
end

--- Close the current tab
function M.close_tab()
  if #vim.api.nvim_list_tabpages() > 1 then
    vim.t.bufs = nil
    utils.event "BufsUpdated"
    vim.cmd.tabclose()
  end
end

--- A table of buffer comparator functions
M.comparator = {}

local fnamemodify = vim.fn.fnamemodify
local function bufinfo(bufnr) return vim.fn.getbufinfo(bufnr)[1] end
local function unique_path(bufnr)
  return require("astronvim.utils.status.provider").unique_path() { bufnr = bufnr }
    .. fnamemodify(bufinfo(bufnr).name, ":t")
end

--- Comparator of two buffer numbers
---@param bufnr_a integer buffer number A
---@param bufnr_b integer buffer number B
---@return boolean comparison true if A is sorted before B, false if B should be sorted before A
function M.comparator.bufnr(bufnr_a, bufnr_b) return bufnr_a < bufnr_b end

--- Comparator of two buffer numbers based on the file extensions
---@param bufnr_a integer buffer number A
---@param bufnr_b integer buffer number B
---@return boolean comparison true if A is sorted before B, false if B should be sorted before A
function M.comparator.extension(bufnr_a, bufnr_b)
  return fnamemodify(bufinfo(bufnr_a).name, ":e") < fnamemodify(bufinfo(bufnr_b).name, ":e")
end

--- Comparator of two buffer numbers based on the full path
---@param bufnr_a integer buffer number A
---@param bufnr_b integer buffer number B
---@return boolean comparison true if A is sorted before B, false if B should be sorted before A
function M.comparator.full_path(bufnr_a, bufnr_b)
  return fnamemodify(bufinfo(bufnr_a).name, ":p") < fnamemodify(bufinfo(bufnr_b).name, ":p")
end

--- Comparator of two buffers based on their unique path
---@param bufnr_a integer buffer number A
---@param bufnr_b integer buffer number B
---@return boolean comparison true if A is sorted before B, false if B should be sorted before A
function M.comparator.unique_path(bufnr_a, bufnr_b) return unique_path(bufnr_a) < unique_path(bufnr_b) end

--- Comparator of two buffers based on modification date
---@param bufnr_a integer buffer number A
---@param bufnr_b integer buffer number B
---@return boolean comparison true if A is sorted before B, false if B should be sorted before A
function M.comparator.modified(bufnr_a, bufnr_b) return bufinfo(bufnr_a).lastused > bufinfo(bufnr_b).lastused end

return M