-- Nursery for random things that may later find their way into stdlib if they mature.

local M = {}

--- Adds one or more blank lines above or below the cursor.
-- TODO: move to _core/defaults.lua once it is possible to assign a Lua function to options #25672
--- @param above? boolean Place blank line(s) above the cursor
local function add_blank(above)
  local offset = above and 1 or 0
  local repeated = vim.fn['repeat']({ '' }, vim.v.count1)
  local linenr = vim.api.nvim_win_get_cursor(0)[1]
  vim.api.nvim_buf_set_lines(0, linenr - offset, linenr - offset, true, repeated)
end

-- TODO: move to _core/defaults.lua once it is possible to assign a Lua function to options #25672
function M.space_above()
  add_blank(true)
end

-- TODO: move to _core/defaults.lua once it is possible to assign a Lua function to options #25672
function M.space_below()
  add_blank()
end

--- Gets a buffer by name
--- @param name string
--- @return integer?
function M.get_buf_by_name(name)
  for _, buf in ipairs(vim.api.nvim_list_bufs()) do
    if vim.api.nvim_buf_get_name(buf) == name then
      return buf
    end
  end
end

--- Edit a file in a specific window
--- @param winnr number
--- @param file string
--- @return number buffer number of the edited buffer
M.edit_in = function(winnr, file)
  local function resolved_path(path)
    if not path or path == '' then
      return ''
    end
    return vim.fn.resolve(vim.fs.abspath(path))
  end

  return vim.api.nvim_win_call(winnr, function()
    local current_buf = vim.api.nvim_win_get_buf(winnr)
    local current = resolved_path(vim.api.nvim_buf_get_name(current_buf))

    -- Check if the current buffer is already the target file
    if current == resolved_path(file) then
      return current_buf
    end

    -- Read the file into the buffer
    vim.cmd.edit(vim.fn.fnameescape(file))
    return vim.api.nvim_get_current_buf()
  end)
end

--- :edit, but it respects commands like :hor, :vert, :tab, etc.
--- @param file string
--- @param mods string|vim.api.keyset.cmd_mods Modifier string ("vertical") or structured mods table.
function M.wrapped_edit(file, mods)
  assert(mods)
  if type(mods) == 'string' then
    mods = vim.api.nvim_parse_cmd(mods .. ' edit').mods --[[@as vim.api.keyset.cmd_mods]]
  end
  --- @cast mods vim.api.keyset.cmd_mods
  if (mods.tab or 0) > 0 or (mods.split or '') ~= '' or mods.horizontal or mods.vertical then
    local buf = M.get_buf_by_name(file)
    if buf == nil then
      buf = vim.api.nvim_create_buf(true, false)
    end
    vim.cmd.sbuffer { buf, mods = mods }
  end
  vim.cmd.edit { file }
end

--- Read a chunk of data from a file
--- @param file string
--- @param size number
--- @return string? chunk or nil on error
function M.read_chunk(file, size)
  local fd = io.open(file, 'rb')
  if not fd then
    return nil
  end
  local chunk = fd:read(size)
  fd:close()
  return tostring(chunk)
end

--- Check if a range in a buffer is inside a Lua codeblock via treesitter injection.
--- Used by :source to detect Lua code in non-Lua files (e.g., vimdoc).
--- @param bufnr integer Buffer number
--- @param line1 integer Start line (1-indexed)
--- @param line2 integer End line (1-indexed)
--- @return boolean True if the range is in a Lua injection
function M.source_is_lua(bufnr, line1, line2)
  local parser = vim.treesitter.get_parser(bufnr)
  if not parser then
    return false
  end
  -- Parse from buffer start through one line past line2 to include injection closing markers
  local range = { line1 - 1, 0, line2 - 1, -1 }
  parser:parse({ 0, 0, line2, -1 })
  local lang_tree = parser:language_for_range(range)
  return lang_tree:lang() == 'lua'
end

--- Returns the exit code string for the current buffer, given:
--- - Channel is attached to the current buffer
--- - Current buffer is a terminal buffer
---
--- @return string
function M.term_exitcode()
  local chan_id = vim.bo.channel
  if chan_id == 0 or vim.bo.buftype ~= 'terminal' then
    return ''
  end

  local info = vim.api.nvim_get_chan_info(chan_id)
  if info.exitcode and info.exitcode >= 0 then
    return string.format('[Exit: %d]', info.exitcode)
  end
  return ''
end

--- Compute a link to a target on a forge host
--- @param repo string URL of repo, usually "https://<domain>/<user>/<name>"
--- @param target string Identifier of a target, like commit hash or tag name
--- @param target_type "commit"|"tag"
--- @return string? # Example: <repo>/releases/tag/<target>
function M.get_forge_url(repo, target, target_type)
  -- The structure <host>/<middle>/<target> works for most forges. Like:
  -- - https://github.com/neovim/nvim-lspconfig/commit/e146efa
  -- - https://github.com/neovim/nvim-lspconfig/releases/tag/v2.8.0
  local ref_middles = {
    { pattern = '^https://github%.com/', commit = 'commit', tag = 'releases/tag' },
    { pattern = '^https://gitlab%.com/', commit = '-/commit', tag = '-/tags' },
    { pattern = '^https://git%.sr%.ht/', commit = 'commit', tag = 'refs' },
    { pattern = '^https://tangled%.org/', commit = 'commit', tag = 'tags' },
    { pattern = '^https://bitbucket%.org/', commit = 'commits', tag = 'src' },

    -- Fall back to Forgejo style since there is no fixed host
    { pattern = '^https://', commit = 'commit', tag = 'src/tag' },
  }

  local middle = ''
  for _, mid in ipairs(ref_middles) do
    if repo:match(mid.pattern) then
      middle = mid[target_type]
      if middle ~= '' then
        break
      end
    end
  end

  if middle == '' then
    return nil
  end
  repo = repo:gsub('/+$', '')
  return ('%s/%s/%s'):format(repo, middle, target)
end

--- Utility function for displaying vim error codes (EXX)
--- @param msg string
function M.echo_err(msg)
  vim.api.nvim_echo({ { msg } }, true, { err = true })
end

--- Define event-handlers (autocmds) ergonomically.
---
--- Examples:
--- ```lua
---   local nvim_on = require('vim._core.util').nvim_on
---   nvim_on('BufWritePost', group, function(ev) print(ev.file) end)
---   nvim_on({ 'BufRead', 'BufNew' }, group, { pattern = '*.lua' }, function(ev) end)
---   nvim_on('VimLeavePre', nil, function() end)
--- ```
---
--- @param events vim.api.keyset.events|vim.api.keyset.events[] Event(s) to watch. See |autocmd-events|.
--- @param group string|integer? Group name or id, or `nil`.
--- @param opts_or_fn vim.api.keyset.create_autocmd Options.
--- @param fn fun(ev: vim.api.keyset.create_autocmd.callback_args): boolean? Event handler.
--- @return integer # Autocmd id (see |nvim_create_autocmd()|).
--- @overload fun(events: vim.api.keyset.events|vim.api.keyset.events[], group: string|integer?, fn: fun(ev: vim.api.keyset.create_autocmd.callback_args): boolean?): integer
function M.nvim_on(events, group, opts_or_fn, fn)
  vim.validate('opts_or_fn', opts_or_fn, { 'function', 'table' })
  local opts --- @type vim.api.keyset.create_autocmd
  if type(opts_or_fn) == 'function' then
    fn, opts = opts_or_fn, {}
  else
    opts = opts_or_fn
  end
  opts.group = group
  opts.callback = fn
  return vim.api.nvim_create_autocmd(events, opts)
end

return M
