4 files changed, 52 insertions, 3 deletions
diff --git a/autoload/prettier.vim b/autoload/prettier.vim
index fae1ef8..0e8ade3 100644
--- a/autoload/prettier.vim
+++ b/autoload/prettier.vim
@@ -69,14 +69,30 @@ function! prettier#Prettier(...) abort
   let l:async = a:0 > 0 ? a:1 : 0
   let l:startSelection = a:0 > 1 ? a:2 : 1
   let l:endSelection = a:0 > 2 ? a:3 : line('$')
+  let l:hasSelection = a:0 > 2 ? 1 : 0
+  let l:partialFormat = a:0 > 3 && a:4 ? a:4 : 0
   let l:config = getbufvar(bufnr('%'), 'prettier_ft_default_args', {})
+  let l:partialFormatEnabled = l:hasSelection && l:partialFormat
 
   if l:execCmd != -1
-    let l:cmd = l:execCmd . prettier#resolver#config#buildCliArgs(prettier#resolver#preset#build(l:config))
+    " TODO
+    " => we should make sure we can resolve --range-start  and --range-end when required
+    "    => when the above is required we should also update l:startSelection to '1' and l:endSelection to line('$')
+    let l:cmd = l:execCmd . prettier#resolver#config#resolve(
+          \ prettier#resolver#preset#resolve(l:config),
+          \ l:partialFormatEnabled,
+          \ l:startSelection, 
+          \ l:endSelection)
 
     " close quickfix if it is opened
     call prettier#utils#quickfix#close()
 
+    " we will be using portion formatting, so we need to send entire buffer to prettier
+    if l:partialFormatEnabled
+      let l:startSelection = 1
+      let l:endSelection = line('$')
+    endif
+
     " format buffer
     call prettier#job#runner#run(l:cmd, l:startSelection, l:endSelection, l:async)
   else
diff --git a/autoload/prettier/resolver/config.vim b/autoload/prettier/resolver/config.vim
index 91fc247..eae6725 100644
--- a/autoload/prettier/resolver/config.vim
+++ b/autoload/prettier/resolver/config.vim
@@ -1,6 +1,6 @@
 " By default we will default to our internal
 " configuration settings for prettier
-function! prettier#resolver#config#buildCliArgs(config) abort
+function! prettier#resolver#config#resolve(config, hasSelection, start, end) abort
   " Allow params to be passed as json format
   " convert bellow usage of globals to a get function o the params defaulting to global
   " TODO: Use a list, filter() and join() to get a nicer list of args.
@@ -8,6 +8,7 @@ function! prettier#resolver#config#buildCliArgs(config) abort
           \ s:Flag_tab_width(a:config) . ' ' .
           \ s:Flag_print_width(a:config) . ' ' .
           \ s:Flag_parser(a:config) . ' ' .
+          \ s:Flag_range_delimiter(a:config, a:hasSelection, a:start, a:end) . ' ' .
           \ ' --semi=' .
           \ get(a:config, 'semi', g:prettier#config#semi) .
           \ ' --single-quote=' .
@@ -34,6 +35,17 @@ function! prettier#resolver#config#buildCliArgs(config) abort
   return l:cmd
 endfunction
 
+" Returns either '--range-start X --range-end Y' or an empty string.
+function! s:Flag_range_delimiter(config, partialFormatEnabled, start, end) abort
+  if (!a:partialFormatEnabled)
+    return ''
+  endif
+
+  let l:range = prettier#utils#buffer#getCharRange(a:start, a:end)
+
+  return '--range-start=' . l:range[0] . ' --range-end=' . l:range[1]
+endfunction
+
 " Returns '--tab-width=NN'
 function! s:Flag_tab_width(config) abort
   let l:value = get(a:config, 'tabWidth', g:prettier#config#tab_width)
diff --git a/autoload/prettier/resolver/preset.vim b/autoload/prettier/resolver/preset.vim
index a0891d2..03f98ee 100644
--- a/autoload/prettier/resolver/preset.vim
+++ b/autoload/prettier/resolver/preset.vim
@@ -1,5 +1,5 @@
 " Build config using predefined preset 
-function! prettier#resolver#preset#build(fileTypeConfigOverwrites) abort
+function! prettier#resolver#preset#resolve(fileTypeConfigOverwrites) abort
   if ( g:prettier#preset#config ==# 'fb' )
     return extend(prettier#presets#fb#config(), a:fileTypeConfigOverwrites)
   endif
diff --git a/autoload/prettier/utils/buffer.vim b/autoload/prettier/utils/buffer.vim
index 1e11ddb..0b3c619 100644
--- a/autoload/prettier/utils/buffer.vim
+++ b/autoload/prettier/utils/buffer.vim
@@ -33,3 +33,24 @@ endfunction
 function! prettier#utils#buffer#createBufferFromUpdatedLines(lines, start, end) abort
   return getbufline(bufnr('%'), 1, a:start - 1) + a:lines + getbufline(bufnr('%'), a:end + 1, '$')
 endfunction
+
+" Adapted from https://github.com/farazdagi/vim-go-ide
+function! s:getCharPosition(line, col)
+    if &encoding !=# 'utf-8'
+        " On utf-8 enconding we can't just use bytes so we need to make sure we can count the
+        " characters, we do that by adding the text into a temporary buffer and counting the chars
+        let l:buf = a:line == 1 ? '' : (join(getline(1, a:line - 1), "\n") . "\n")
+        let l:buf .= a:col == 1 ? '' : getline('.')[:a:col - 2]
+        return len(iconv(l:buf, &encoding, 'utf-8'))
+    endif
+    " On non utf-8 the line byte should match the character
+    return line2byte(a:line) + (a:col - 2)
+endfun
+
+" Returns [start, end] byte range when on visual mode
+function! prettier#utils#buffer#getCharRange(startSelection, endSelection) abort
+  let l:range = []
+  call add(l:range, s:getCharPosition(a:startSelection, col("'<")))
+  call add(l:range, s:getCharPosition(a:endSelection, col("'>")))
+  return l:range
+endfunction