feat: new adapter for S3 buckets (#677)

* Added s3 support

* Save work

* Various bug fixes

* Minor cleanup

* Minor bug fixes

* Fix typo

* Update following feedback + minor bug fix

* Fix CI

* Cleanup and remove bucket entry_type

* Make suggested changes

* Better aws existence check

* Fix typo

* refactor: don't bother caching aws executable status

---------

Co-authored-by: Steven Arcangeli <506791+stevearc@users.noreply.github.com>

lua/oil/adapters/s3/s3fs.lua

@@ -0,0 +1,149 @@
+local cache = require("oil.cache")
+local config = require("oil.config")
+local constants = require("oil.constants")
+local shell = require("oil.shell")
+local util = require("oil.util")
+
+local M = {}
+
+local FIELD_META = constants.FIELD_META
+
+---@param line string
+---@return string Name of entry
+---@return oil.EntryType
+---@return table Metadata for entry
+local function parse_ls_line_bucket(line)
+  local date, name = line:match("^(%d+%-%d+%-%d+%s%d+:%d+:%d+)%s+(.*)$")
+  if not date or not name then
+    error(string.format("Could not parse '%s'", line))
+  end
+  local type = "directory"
+  local meta = { date = date }
+  return name, type, meta
+end
+
+---@param line string
+---@return string Name of entry
+---@return oil.EntryType
+---@return table Metadata for entry
+local function parse_ls_line_file(line)
+  local name = line:match("^%s+PRE%s+(.*)/$")
+  local type = "directory"
+  local meta = {}
+  if name then
+    return name, type, meta
+  end
+  local date, size
+  date, size, name = line:match("^(%d+%-%d+%-%d+%s%d+:%d+:%d+)%s+(%d+)%s+(.*)$")
+  if not name then
+    error(string.format("Could not parse '%s'", line))
+  end
+  type = "file"
+  meta = { date = date, size = tonumber(size) }
+  return name, type, meta
+end
+
+---@param cmd string[] cmd and flags
+---@return string[] Shell command to run
+local function create_s3_command(cmd)
+  local full_cmd = vim.list_extend({ "aws", "s3" }, cmd)
+  return vim.list_extend(full_cmd, config.extra_s3_args)
+end
+
+---@param url string
+---@param path string
+---@param callback fun(err?: string, entries?: oil.InternalEntry[], fetch_more?: fun())
+function M.list_dir(url, path, callback)
+  local cmd = create_s3_command({ "ls", path, "--color=off", "--no-cli-pager" })
+  shell.run(cmd, function(err, lines)
+    if err then
+      return callback(err)
+    end
+    assert(lines)
+    local cache_entries = {}
+    local url_path, _
+    _, url_path = util.parse_url(url)
+    local is_top_level = url_path == nil or url_path:match("/") == nil
+    local parse_ls_line = is_top_level and parse_ls_line_bucket or parse_ls_line_file
+    for _, line in ipairs(lines) do
+      if line ~= "" then
+        local name, type, meta = parse_ls_line(line)
+        -- in s3 '-' can be used to create an "empty folder"
+        if name ~= "-" then
+          local cache_entry = cache.create_entry(url, name, type)
+          table.insert(cache_entries, cache_entry)
+          cache_entry[FIELD_META] = meta
+        end
+      end
+    end
+    callback(nil, cache_entries)
+  end)
+end
+
+--- Create files
+---@param path string
+---@param callback fun(err: nil|string)
+function M.touch(path, callback)
+  -- here "-" means that we copy from stdin
+  local cmd = create_s3_command({ "cp", "-", path })
+  shell.run(cmd, { stdin = "null" }, callback)
+end
+
+--- Remove files
+---@param path string
+---@param is_folder boolean
+---@param callback fun(err: nil|string)
+function M.rm(path, is_folder, callback)
+  local main_cmd = { "rm", path }
+  if is_folder then
+    table.insert(main_cmd, "--recursive")
+  end
+  local cmd = create_s3_command(main_cmd)
+  shell.run(cmd, callback)
+end
+
+--- Remove bucket
+---@param bucket string
+---@param callback fun(err: nil|string)
+function M.rb(bucket, callback)
+  local cmd = create_s3_command({ "rb", bucket })
+  shell.run(cmd, callback)
+end
+
+--- Make bucket
+---@param bucket string
+---@param callback fun(err: nil|string)
+function M.mb(bucket, callback)
+  local cmd = create_s3_command({ "mb", bucket })
+  shell.run(cmd, callback)
+end
+
+--- Move files
+---@param src string
+---@param dest string
+---@param is_folder boolean
+---@param callback fun(err: nil|string)
+function M.mv(src, dest, is_folder, callback)
+  local main_cmd = { "mv", src, dest }
+  if is_folder then
+    table.insert(main_cmd, "--recursive")
+  end
+  local cmd = create_s3_command(main_cmd)
+  shell.run(cmd, callback)
+end
+
+--- Copy files
+---@param src string
+---@param dest string
+---@param is_folder boolean
+---@param callback fun(err: nil|string)
+function M.cp(src, dest, is_folder, callback)
+  local main_cmd = { "cp", src, dest }
+  if is_folder then
+    table.insert(main_cmd, "--recursive")
+  end
+  local cmd = create_s3_command(main_cmd)
+  shell.run(cmd, callback)
+end
+
+return M