" Zlib License
"
" Copyright (c) 2026 Nicolás A. Ortega <nicolas@ortegas.org>
"
" This software is provided 'as-is', without any express or implied warranty. In
" no event will the authors be held liable for any damages arising from the use
" of this software.
"
" Permission is granted to anyone to use this software for any purpose, including
" commercial applications, and to alter it and redistribute it freely, subject
" to the following restrictions:
"
" 1. The origin of this software must not be misrepresented; you must not claim
"    that you wrote the original software. If you use this software in a product,
"    an acknowledgment in the product documentation would be appreciated but is
"    not required.
"
" 2. Altered source versions must be plainly marked as such, and must not be
"    misrepresented as being the original software.
"
" 3. This notice may not be removed or altered from any source distribution.
" vim-licenser: A plugin for adding license headers to source code files

" Usage:
"   :Licenser <license>
"
" Available licenses can be found in the licenses/ directory

if exists('g:loaded_licenser')
	finish
endif
let g:loaded_licenser = 1

function! s:GetCommentStyle(filetype) abort
	let ft = a:filetype

	" Define comment styles for different filetypes
	"  - margin: if prefix and suffix should be used
	"  - hashbang: if the file has a hashbang line, we should skip it when
	"  adding the license header
	"  - prefix: the string to use at the beginning of the comment block
	"  - middle: the string to use at the beginning of each line in the comment
	"  - suffix: the string to use at the end of the comment block
	let comment_styles = {
		\ 'bash': {'margin': 0, 'hashbang': 1, 'prefix': '', 'middle': '#', 'suffix': ''},
		\ 'c': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'cpp': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'csharp': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'css': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'dart': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'go': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'groovy': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'haskell': {'margin': 0, 'hashbang': 1, 'prefix': '', 'middle': '--', 'suffix': ''},
		\ 'html': {'margin': 1, 'hashbang': 0, 'prefix': '<!--', 'middle': ' *', 'suffix': '-->'},
		\ 'java': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'javascript': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'json': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'kotlin': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'lua': {'margin': 0, 'hashbang': 1, 'prefix': '', 'middle': '--', 'suffix': ''},
		\ 'matlab': {'margin': 0, 'hashbang': 0, 'prefix': '', 'middle': '%', 'suffix': ''},
		\ 'perl': {'margin': 0, 'hashbang': 1, 'prefix': '', 'middle': '#', 'suffix': ''},
		\ 'php': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'python': {'margin': 0, 'hashbang': 1, 'prefix': '', 'middle': '#', 'suffix': ''},
		\ 'r': {'margin': 0, 'hashbang': 0, 'prefix': '', 'middle': '#', 'suffix': ''},
		\ 'ruby': {'margin': 0, 'hashbang': 1, 'prefix': '', 'middle': '#', 'suffix': ''},
		\ 'rust': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'scala': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'shell': {'margin': 0, 'hashbang': 1, 'prefix': '', 'middle': '#', 'suffix': ''},
		\ 'sql': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'swift': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'typescript': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'typescriptreact': {'margin': 1, 'hashbang': 0, 'prefix': '/*', 'middle': ' *', 'suffix': ' */'},
		\ 'vim': {'margin': 0, 'hashbang': 0, 'prefix': '', 'middle': '"', 'suffix': ''},
		\ 'xml': {'margin': 1, 'hashbang': 0, 'prefix': '<!--', 'middle': '  ', 'suffix': '-->'},
		\ 'yaml': {'margin': 0, 'hashbang': 0, 'prefix': '', 'middle': '#', 'suffix': ''},
	\ }
	if has_key(comment_styles, ft)
		return comment_styles[ft]
	else
		" Error message for unsupported filetypes
		echohl ErrorMsg
		echo 'Unsupported filetype: ' . ft
		echohl None
		return {'margin': 0, 'prefix': '', 'middle': '', 'suffix': ''}
	endif
endfunction

function! s:AddLicenseHeader(license) abort
	let plugin_dir = fnamemodify(expand('<sfile>'), ':h:h')
	let license_file = plugin_dir . '/licenses/' . a:license . '.txt'

	if !filereadable(license_file)
		echohl ErrorMsg
		echo 'License file not found: ' . license_file
		echohl None
		return
	endif

	let license_lines = readfile(license_file)
	let author = get(g:, 'licenser_author', 'Author Name')
	let year = strftime('%Y')

	let comment_style = s:GetCommentStyle(&filetype)

	let processed_lines = []

	if comment_style.margin
		call add(processed_lines, comment_style.prefix)
	endif

	for line in license_lines
		let line = substitute(line, 'YEAR', year, 'g')
		let line = substitute(line, 'AUTHOR', author, 'g')

		if line ==# ''
			call add(processed_lines, comment_style.middle)
		else
			call add(processed_lines, comment_style.middle . ' ' . line)
		endif
	endfor

	if comment_style.margin
		call add(processed_lines, comment_style.suffix)
	endif

	call append(comment_style.hashbang, processed_lines)
endfunction

function! s:CompleteFiletype(A, L, P) abort
	let plugin_dir = fnamemodify(expand('<sfile>'), ':h:h')
	let licenses_dir = plugin_dir . '/licenses/'

	if !isdirectory(licenses_dir)
		return []
	endif

	let licenses = []
	for file in glob(licenses_dir . '*.txt', 0, 1)
		let name = fnamemodify(file, ':t:r')
		if name =~ '^' . a:A
			call add(licenses, name)
		endif
	endfor

	return sort(licenses)
endfunction

command! -nargs=1 -complete=customlist,s:CompleteFiletype Licenser call s:AddLicenseHeader(<q-args>)