--  Updates version.c list of applied Vim patches.
--
--  Usage:
--    VIM_SOURCE_DIR=~/neovim/.vim-src/ nvim -l ./scripts/vimpatch.lua

local nvim = vim.api

local function systemlist(...)
  local rv = nvim.nvim_call_function('systemlist', ...)
  local err = nvim.nvim_get_vvar('shell_error')
  local args_str = nvim.nvim_call_function('string', ...)
  if 0 ~= err then
    error('command failed: ' .. args_str)
  end
  return rv
end

local function vimpatch_sh_list_tokens()
  return systemlist({ { 'bash', '-c', 'scripts/vim-patch.sh -M' } })
end

-- Generates the lines to be inserted into the src/nvim/version.c
-- `included_patches[]` definition.
local function gen_version_c_lines()
  -- Sets of merged Vim x.y.zzzz patch numbers.
  local merged_patch_sets = {}
  for _, token in ipairs(vimpatch_sh_list_tokens()) do
    local major_version, minor_version, patch_num = string.match(token, '^(%d+).(%d+).(%d+)$')
    local n = tonumber(patch_num)
    -- TODO(@janlazo): Allow multiple Vim versions
    -- if n then
    if n and major_version == '8' and minor_version == '1' then
      local major_minor_version = major_version * 100 + minor_version
      merged_patch_sets[major_minor_version] = merged_patch_sets[major_minor_version] or {}
      table.insert(merged_patch_sets[major_minor_version], n)
    end
  end

  local sorted_versions = {}
  for k, _ in pairs(merged_patch_sets) do
    table.insert(sorted_versions, k)
  end
  table.sort(sorted_versions)
  local lines = {}
  for _, major_minor_version in ipairs(sorted_versions) do
    -- table.insert(lines, string.format('  // major minor version: %s', major_minor_version))
    local patch_set = merged_patch_sets[major_minor_version]
    for i = #patch_set, 1, -1 do
      local patch = patch_set[i]
      table.insert(lines, string.format('  %s,', patch))
      if patch > 0 then
        local oldest_unmerged_patch = patch_set[i - 1] and (patch_set[i - 1] + 1) or 0
        for unmerged_patch = patch -1, oldest_unmerged_patch, -1 do
          table.insert(lines, string.format('  // %s,', unmerged_patch))
        end
      end
    end
  end

  return lines
end

local function patch_version_c()
  local lines = gen_version_c_lines()

  nvim.nvim_command('silent noswapfile noautocmd edit src/nvim/version.c')
  nvim.nvim_command('/static const int included_patches')
  -- Delete the existing lines.
  nvim.nvim_command('silent normal! j0d/};\rk')
  -- Insert the lines.
  nvim.nvim_call_function('append', {
    nvim.nvim_eval('line(".")'),
    lines,
  })
  nvim.nvim_command('silent write')
end

patch_version_c()