" scripts/download_bin.vim — install `nuwiki-ls` from a release tarball,
" falling back to `cargo build --release` from the nuwiki-rs repo.
"
" Invoked by Dein / vim-plug build hooks:
"   vim -e -s -c "source scripts/download_bin.vim" -c "q"
"
" That invocation runs in 'compatible' mode, where leading-backslash line
" continuations aren't recognised (they'd raise E10, and any error in silent
" Ex mode makes Vim exit non-zero — a spurious build failure). Reset
" 'cpoptions' to the Vim default for the duration so the script parses, and
" restore it at the end.
let s:cpo_save = &cpo
set cpo&vim

let s:plugin_dir = fnamemodify(resolve(expand('<sfile>:p')), ':h:h')
let s:bin_dir    = s:plugin_dir . '/bin'
let s:suffix     = has('win32') ? '.exe' : ''
let s:bin        = s:bin_dir . '/nuwiki-ls' . s:suffix
let s:rs_repo    = fnamemodify(s:plugin_dir, ':h:h') . '/nuwiki-rs'

call mkdir(s:bin_dir, 'p')

function! s:is_musl(arch) abort
  if filereadable('/lib/ld-musl-' . a:arch . '.so.1')
    return 1
  endif
  if !executable('ldd')
    return 0
  endif
  " musl's ldd writes its banner to stderr.
  return stridx(system('ldd --version 2>&1'), 'musl') >= 0
endfunction

" NixOS and Guix System are not FHS distributions: glibc lives in the store,
" so the /lib64/ld-linux-*.so.2 a generic -gnu binary is linked against is
" either absent or — on NixOS — a stub that only prints an error and exits
" 127. `ldd --version` still reports GNU libc there, so libc detection alone
" picks the wrong asset. The musl builds are statically linked and need no
" loader at all, so they run on these systems unchanged.
function! s:is_non_fhs_linux() abort
  if filereadable('/etc/NIXOS')
    return 1
  endif
  if !filereadable('/etc/os-release')
    return 0
  endif
  for l:line in readfile('/etc/os-release')
    let l:id = matchstr(l:line, '^ID=\s*"\?\zs[[:alnum:]._-]\+')
    if l:id ==# 'nixos' || l:id ==# 'guix'
      return 1
    endif
  endfor
  return 0
endfunction

" Release triples to try, best first. More than one entry means the later ones
" are fallbacks for a host that turns out not to be able to run the first.
function! s:targets() abort
  if get(g:, 'nuwiki_ls_target', '') !=# ''
    return [g:nuwiki_ls_target]
  endif
  if has('win32')
    return ['x86_64-pc-windows-msvc']
  elseif has('mac')
    return [has('arm64') ? 'aarch64-apple-darwin' : 'x86_64-apple-darwin']
  elseif has('linux')
    let l:uname_m = trim(system('uname -m'))
    let l:arch = (l:uname_m ==# 'aarch64' || l:uname_m ==# 'arm64')
          \ ? 'aarch64' : 'x86_64'
    let l:musl = l:arch . '-unknown-linux-musl'
    if s:is_musl(l:arch) || s:is_non_fhs_linux()
      return [l:musl]
    endif
    " Static musl runs anywhere, so keep it as a last resort on glibc hosts
    " too (old glibc, exotic loader layouts).
    return [l:arch . '-unknown-linux-gnu', l:musl]
  endif
  return []
endfunction

" Can this host actually start the binary? Exit codes 126 and 127 mean the
" kernel or the dynamic loader refused to exec it (missing/stub loader, wrong
" architecture); any other code means it ran and exited on its own terms.
" system() gives the child an empty stdin, so the LSP loop sees EOF and stops.
function! s:can_exec(path) abort
  call system(shellescape(a:path) . ' --version')
  return v:shell_error != 126 && v:shell_error != 127
endfunction

function! s:build_from_source() abort
  if !executable('cargo')
    echohl ErrorMsg | echom 'nuwiki: cargo not found, cannot build from source' | echohl None
    return 0
  endif
  echom 'nuwiki: cloning nuwiki-rs …'
  if !filereadable(s:rs_repo . '/Cargo.toml')
    call system('git clone --depth 1 https://code.gfran.co/gffranco/nuwiki-rs.git ' . shellescape(s:rs_repo))
    if v:shell_error != 0
      echohl ErrorMsg | echom 'nuwiki: failed to clone nuwiki-rs' | echohl None
      return 0
    endif
  endif
  echom 'nuwiki: cargo build --release …'
  call system('cargo build --release -p nuwiki-ls --manifest-path ' . shellescape(s:rs_repo . '/Cargo.toml'))
  if v:shell_error != 0
    echohl ErrorMsg | echom 'nuwiki: cargo build failed' | echohl None
    return 0
  endif
  let l:built = s:rs_repo . '/target/release/nuwiki-ls' . s:suffix
  call system('cp ' . shellescape(l:built) . ' ' . shellescape(s:bin))
  call system('chmod +x ' . shellescape(s:bin))
  return executable(s:bin)
endfunction

function! s:download_release(target) abort
  if !executable('curl') || !executable('tar')
    return 0
  endif
  let l:url = 'https://code.gfran.co/gffranco/nuwiki-rs/releases/download/latest/nuwiki-ls-'
        \ . a:target . '.tar.gz'
  let l:archive = tempname() . '.tar.gz'
  call system('curl -fsSL -o ' . shellescape(l:archive) . ' ' . shellescape(l:url))
  if v:shell_error != 0
    return 0
  endif
  let l:extract = tempname()
  call mkdir(l:extract, 'p')
  call system('tar -xzf ' . shellescape(l:archive) . ' -C ' . shellescape(l:extract))
  if v:shell_error != 0
    return 0
  endif
  " Vet the staged copy before it becomes the installed one, so a binary this
  " host cannot exec never lands at s:bin for the LSP client to pick up.
  let l:staged = l:extract . '/nuwiki-ls' . s:suffix
  call system('chmod +x ' . shellescape(l:staged))
  if !executable(l:staged) || !s:can_exec(l:staged)
    return 0
  endif
  call system('cp ' . shellescape(l:staged) . ' ' . shellescape(s:bin))
  call system('chmod +x ' . shellescape(s:bin))
  return executable(s:bin)
endfunction

let s:installed = 0
for s:t in s:targets()
  if s:download_release(s:t)
    echom 'nuwiki: installed ' . s:bin . ' (' . s:t . ')'
    let s:installed = 1
    break
  endif
endfor

if !s:installed
  echohl WarningMsg | echom 'nuwiki: download failed, falling back to source build' | echohl None
  if !s:build_from_source()
    echohl ErrorMsg | echom 'nuwiki: install failed' | echohl None
  endif
endif

let &cpo = s:cpo_save