Start using prettier default arguments

This is one approach for handling default prettier arguments.

It is a little verbose, but I think ejecting the flags that don't have
to be set by the editor (in favor of .prettierrc files) is a win.

4 files changed, 122 insertions, 114 deletions

diff --git a/README.md b/README.md
index c7c9997..a2917ae 100644
--- a/README.md
+++ b/README.md
@@ -168,50 +168,31 @@ autocmd BufWritePre,TextChanged,InsertLeave *.js,*.jsx,*.mjs,*.ts,*.tsx,*.css,*.
 However they can be configured by:
 
 ```vim
-" max line length that prettier will wrap on
-" Prettier default: 80
-let g:prettier#config#print_width = 80
+" Max line length that prettier will wrap on: a number or 'auto' (use
+" textwidth).
+" default: 'auto'
+let g:prettier#config#print_width = 'auto'
 
-" number of spaces per indentation level
-" Prettier default: 2
-let g:prettier#config#tab_width = 2
+" number of spaces per indentation level: a number or 'auto' (use
+" softtabstop)
+" default: 'auto'
+let g:prettier#config#tab_width = 'auto'
 
-" use tabs over spaces
-" Prettier default: false
-let g:prettier#config#use_tabs = 'false'
+" use tabs instead of spaces: true, false, or auto (use the expandtab setting).
+" default: 'auto'
+let g:prettier#config#use_tabs = 'auto'
 
-" print semicolons
-" Prettier default: true
-let g:prettier#config#semi = 'true'
-
-" single quotes over double quotes
-" Prettier default: false
-let g:prettier#config#single_quote = 'true'
-
-" print spaces between brackets
-" Prettier default: true
-let g:prettier#config#bracket_spacing = 'false'
-
-" put > on the last line instead of new line
-" Prettier default: false
-let g:prettier#config#jsx_bracket_same_line = 'true'
-
-" avoid|always
-" Prettier default: avoid
-let g:prettier#config#arrow_parens = 'always'
-
-" none|es5|all
-" Prettier default: none
-let g:prettier#config#trailing_comma = 'all'
-
-" flow|babylon|typescript|css|less|scss|json|graphql|markdown
-" Prettier default: babylon
-let g:prettier#config#parser = 'flow'
+" flow|babylon|typescript|css|less|scss|json|graphql|markdown or empty string
+" (let prettier choose).
+" default: ''
+let g:prettier#config#parser = ''
 
 " cli-override|file-override|prefer-file
-let g:prettier#config#config_precedence = 'prefer-file'
+" default: 'cli-override'
+let g:prettier#config#config_precedence = 'cli-override'
 
 " always|never|preserve
+" default: 'preserve'
 let g:prettier#config#prose_wrap = 'preserve'
 ```
 
diff --git a/autoload/prettier.vim b/autoload/prettier.vim
index 4b5a4e9..7cf9cca 100644
--- a/autoload/prettier.vim
+++ b/autoload/prettier.vim
@@ -287,36 +287,81 @@ function! s:Apply_Prettier_Format(lines, startSelection, endSelection) abort
   call winrestview(l:winview)
 endfunction
 
+" Returns either '--use-tabs' or an empty string.
+function! s:Flag_use_tabs(config) abort
+  let l:value = get(a:config, 'useTabs', g:prettier#config#use_tabs)
+  if (l:value ==# 'auto')
+    let l:value = &expandtab ? 'false' : 'true'
+  endif
+
+  if ( l:value ==# 'true' )
+    return '--use-tabs'
+  else
+    return ''
+  endif
+endfunction
+
+" Backwards compatable version of shiftwidth()
+function! s:sw() abort
+  if exists('*shiftwidth')
+    return shiftwidth()
+  else
+    return &shiftwidth
+  endif
+endfunction
+
+" Returns '--tab-width=NN'
+function! s:Flag_tab_width(config) abort
+  let l:value = get(a:config, 'tabWidth', g:prettier#config#tab_width)
+
+  if (l:value ==# 'auto')
+    let l:value = s:sw()
+  endif
+
+  return '--tab-width=' . l:value
+endfunction
+
+" Returns '--print-width=NN' or ''
+function! s:Flag_print_width(config) abort
+  let l:value = get(a:config, 'printWidth', g:prettier#config#print_width)
+
+  if (l:value ==# 'auto')
+    let l:value = &textwidth
+  endif
+
+  if (l:value > 0)
+    return '--print-width=' . l:value
+  else
+    return ''
+  endif
+endfunction
+
+" Returns '--parser=PARSER' or ''
+function! s:Flag_parser(config) abort
+  let l:value = get(a:config, 'parser', g:prettier#config#parser)
+
+  if (l:value !=# '')
+    return '--parser=' . l:value
+  else
+    return ''
+  endif
+endfunction
+
 " By default we will default to our internal
 " configuration settings for prettier
 function! s:Get_Prettier_Exec_Args(config) abort
   " Allow params to be passed as json format
   " convert bellow usage of globals to a get function o the params defaulting to global
-  let l:cmd = ' --print-width ' .
-          \ get(a:config, 'printWidth', g:prettier#config#print_width) .
-          \ ' --tab-width ' .
-          \ get(a:config, 'tabWidth', g:prettier#config#tab_width) .
-          \ ' --use-tabs ' .
-          \ get(a:config, 'useTabs', g:prettier#config#use_tabs) .
-          \ ' --semi ' .
-          \ get(a:config, 'semi', g:prettier#config#semi) .
-          \ ' --single-quote ' .
-          \ get(a:config, 'singleQuote', g:prettier#config#single_quote) .
-          \ ' --bracket-spacing ' .
-          \ get(a:config, 'bracketSpacing', g:prettier#config#bracket_spacing) .
-          \ ' --jsx-bracket-same-line ' .
-          \ get(a:config, 'jsxBracketSameLine', g:prettier#config#jsx_bracket_same_line) .
-          \ ' --arrow-parens ' .
-          \ get(a:config, 'arrowParens', g:prettier#config#arrow_parens) .
-          \ ' --trailing-comma ' .
-          \ get(a:config, 'trailingComma', g:prettier#config#trailing_comma) .
-          \ ' --parser ' .
-          \ get(a:config, 'parser', g:prettier#config#parser) .
-          \ ' --config-precedence ' .
+  " TODO: Use a list, filter() and join() to get a nicer list of args.
+  let l:cmd = s:Flag_use_tabs(a:config) . ' ' .
+          \ s:Flag_tab_width(a:config) . ' ' .
+          \ s:Flag_print_width(a:config) . ' ' .
+          \ s:Flag_parser(a:config) . ' ' .
+          \ ' --config-precedence=' .
           \ get(a:config, 'configPrecedence', g:prettier#config#config_precedence) .
-          \ ' --prose-wrap ' .
+          \ ' --prose-wrap=' .
           \ get(a:config, 'proseWrap', g:prettier#config#prose_wrap) .
-          \ ' --stdin-filepath ' .
+          \ ' --stdin-filepath=' .
           \ simplify(expand('%:p')) .
           \ ' --no-editorconfig '.
           \ ' --loglevel error '.
diff --git a/doc/prettier.txt b/doc/prettier.txt
index 99b8d70..85280de 100644
--- a/doc/prettier.txt
+++ b/doc/prettier.txt
@@ -138,40 +138,31 @@ Overwrite default prettier configuration
 **Note:** vim-prettier default settings differ from prettier intentionally. 
 However they can be configured by:
 >
-  " max line length that prettier will wrap on
-  let g:prettier#config#print_width = 80
+  " Max line length that prettier will wrap on: a number or 'auto' (use
+  " textwidth).
+  " default: 'auto'
+  let g:prettier#config#print_width = 'auto'
 
-  " number of spaces per indentation level
-  let g:prettier#config#tab_width = 2
+  " number of spaces per indentation level: a number or 'auto' (use
+  " softtabstop)
+  " default: 'auto'
+  let g:prettier#config#tab_width = 'auto'
 
-  " use tabs over spaces
-  let g:prettier#config#use_tabs = 'false'
+  " use tabs instead of spaces: true, false, or auto (use the expandtab setting).
+  " default: 'auto'
+  let g:prettier#config#use_tabs = 'auto'
 
-  " print semicolons
-  let g:prettier#config#semi = 'true'
-
-  " single quotes over double quotes
-  let g:prettier#config#single_quote = 'true' 
-
-  " print spaces between brackets
-  let g:prettier#config#bracket_spacing = 'false' 
-
-  " put > on the last line instead of new line
-  let g:prettier#config#jsx_bracket_same_line = 'true'
-
-  " avoid|always
-  let g:prettier#config#arrow_parens = 'always'
-
-  " none|es5|all
-  let g:prettier#config#trailing_comma = 'all'
-
-  " flow|babylon|typescript|css|less|scss|json|graphql|markdown
-  let g:prettier#config#parser = 'flow'
+  " flow|babylon|typescript|css|less|scss|json|graphql|markdown or empty string
+  " (let prettier choose).
+  " default: ''
+  let g:prettier#config#parser = ''
 
   " cli-override|file-override|prefer-file
-  let g:prettier#config#config_precedence = 'prefer-file'
+  " default: 'cli-override'
+  let g:prettier#config#config_precedence = 'cli-override'
 
   " always|never|preserve
+  " default: 'preserve'
   let g:prettier#config#prose_wrap = 'preserve'
 <
 ==============================================================================
diff --git a/plugin/prettier.vim b/plugin/prettier.vim
index da008fe..08144aa 100644
--- a/plugin/prettier.vim
+++ b/plugin/prettier.vim
@@ -33,40 +33,31 @@ let g:prettier#exec_cmd_async = get(g:, 'prettier#exec_cmd_async', 0)
 let g:prettier#quickfix_enabled = get(g:, 'prettier#quickfix_enabled', 1)
 
 " => Prettier CLI config
-" max line lengh that prettier will wrap on
-let g:prettier#config#print_width = get(g:, 'prettier#config#print_width', 80)
+" Max line length that prettier will wrap on: a number or 'auto' (use
+" textwidth).
+" default: 'auto'
+let g:prettier#config#print_width = get(g:, 'prettier#config#print_width', 'auto')
 
-" number of spaces per indentation level
-let g:prettier#config#tab_width = get(g:,'prettier#config#tab_width', 2)
+" number of spaces per indentation level: a number or 'auto' (use
+" softtabstop)
+" default: 'auto'
+let g:prettier#config#tab_width = get(g:,'prettier#config#tab_width', 'auto')
 
-" use tabs over spaces
-let g:prettier#config#use_tabs = get(g:,'prettier#config#use_tabs', 'false')
+" use tabs instead of spaces: true, false, or auto (use the expandtab setting).
+" default: 'auto'
+let g:prettier#config#use_tabs = get(g:,'prettier#config#use_tabs', 'auto')
 
-" print semicolons
-let g:prettier#config#semi = get(g:,'prettier#config#semi', 'true')
-
-" single quotes over double quotes
-let g:prettier#config#single_quote = get(g:,'prettier#config#single_quote', 'true')
-
-" print spaces between brackets
-let g:prettier#config#bracket_spacing = get(g:,'prettier#config#bracket_spacing', 'false')
-
-" put > on the last line instead of new line
-let g:prettier#config#jsx_bracket_same_line = get(g:,'prettier#config#jsx_bracket_same_line', 'true')
-
-" avoid wrapping a single arrow function param in parens
-let g:prettier#config#arrow_parens = get(g:,'prettier#config#arrow_parens', 'avoid')
-
-" none|es5|all
-let g:prettier#config#trailing_comma = get(g:,'prettier#config#trailing_comma', 'all')
-
-" flow|babylon|typescript|postcss|json|graphql
-let g:prettier#config#parser = get(g:,'prettier#config#parser', 'flow')
+" flow|babylon|typescript|css|less|scss|json|graphql|markdown or empty string
+" (let prettier choose).
+" default: ''
+let g:prettier#config#parser = get(g:,'prettier#config#parser', '')
 
 " cli-override|file-override|prefer-file
-let g:prettier#config#config_precedence = get(g:, 'prettier#config#config_precedence', 'prefer-file')
+" default: 'cli-override'
+let g:prettier#config#config_precedence = get(g:, 'prettier#config#config_precedence', 'cli-override')
 
 " always|never|preserve
+" default: 'preserve'
 let g:prettier#config#prose_wrap = get(g:, 'prettier#config#prose_wrap', 'preserve')
 
 " Don't leave the quicklist focused on error.