" Author: w0rp <devw0rp@gmail.com>
" Description: This file adds support for using the shellcheck linter with
"   shell scripts.

" This global variable can be set with a string of comma-separated error
" codes to exclude from shellcheck. For example:
"
" let g:ale_sh_shellcheck_exclusions = 'SC2002,SC2004'
let g:ale_sh_shellcheck_exclusions =
\   get(g:, 'ale_sh_shellcheck_exclusions', get(g:, 'ale_linters_sh_shellcheck_exclusions', ''))

let g:ale_sh_shellcheck_executable =
\   get(g:, 'ale_sh_shellcheck_executable', 'shellcheck')

let g:ale_sh_shellcheck_options =
\   get(g:, 'ale_sh_shellcheck_options', '')

let s:version_cache = {}

function! ale_linters#sh#shellcheck#GetExecutable(buffer) abort
    return ale#Var(a:buffer, 'sh_shellcheck_executable')
endfunction

function! ale_linters#sh#shellcheck#GetDialectArgument(buffer) abort
    let l:shell_type = ale#handlers#sh#GetShellType(a:buffer)

    if !empty(l:shell_type)
        " Use the dash dialect for /bin/ash, etc.
        if l:shell_type is# 'ash'
            return 'dash'
        endif

        return l:shell_type
    endif

    " If there's no hashbang, try using Vim's buffer variables.
    if getbufvar(a:buffer, 'is_bash', 0)
        return 'bash'
    elseif getbufvar(a:buffer, 'is_sh', 0)
        return 'sh'
    elseif getbufvar(a:buffer, 'is_kornshell', 0)
        return 'ksh'
    endif

    return ''
endfunction

function! ale_linters#sh#shellcheck#VersionCheck(buffer) abort
    let l:executable = ale_linters#sh#shellcheck#GetExecutable(a:buffer)

    " Don't check the version again if we've already cached it.
    if has_key(s:version_cache, l:executable)
        return ''
    endif

    return ale#Escape(l:executable) . ' --version'
endfunction

" Get the shellcheck version from the cache, or parse it and cache it.
function! s:GetVersion(executable, output) abort
    let l:version = get(s:version_cache, a:executable, [])

    for l:match in ale#util#GetMatches(a:output, '\v\d+\.\d+\.\d+')
        let l:version = ale#semver#Parse(l:match[0])
        let s:version_cache[a:executable] = l:version
    endfor

    return l:version
endfunction

function! s:CanUseExternalOption(version) abort
    return !empty(a:version)
    \   && ale#semver#GreaterOrEqual(a:version, [0, 4, 0])
endfunction

function! ale_linters#sh#shellcheck#GetCommand(buffer, version_output) abort
    let l:executable = ale_linters#sh#shellcheck#GetExecutable(a:buffer)
    let l:version = s:GetVersion(l:executable, a:version_output)

    let l:options = ale#Var(a:buffer, 'sh_shellcheck_options')
    let l:exclude_option = ale#Var(a:buffer, 'sh_shellcheck_exclusions')
    let l:dialect = ale_linters#sh#shellcheck#GetDialectArgument(a:buffer)
    let l:external_option = s:CanUseExternalOption(l:version) ? ' -x' : ''

    return ale#path#BufferCdString(a:buffer)
    \   . ale#Escape(l:executable)
    \   . (!empty(l:dialect) ? ' -s ' . l:dialect : '')
    \   . (!empty(l:options) ? ' ' . l:options : '')
    \   . (!empty(l:exclude_option) ? ' -e ' . l:exclude_option : '')
    \   . l:external_option
    \   . ' -f gcc -'
endfunction

call ale#linter#Define('sh', {
\   'name': 'shellcheck',
\   'executable_callback': 'ale_linters#sh#shellcheck#GetExecutable',
\   'command_chain': [
\       {'callback': 'ale_linters#sh#shellcheck#VersionCheck'},
\       {'callback': 'ale_linters#sh#shellcheck#GetCommand'},
\   ],
\   'callback': 'ale#handlers#gcc#HandleGCCFormat',
\})