-- REQUIRED PLUGINS (via your plugin manager, e.g., Packer/Lazy):
-- 1. 'hrsh7th/nvim-cmp'        (The completion engine)
-- 2. 'hrsh7th/cmp-nvim-lsp'    (Bridge between LSP and cmp)
-- 3. 'neovim/nvim-lspconfig'   (Configs for ZLS)
-- 4. 'L3MON4D3/LuaSnip'        (Snippet engine, required by cmp)

local cmp = require('cmp')
local lspconfig = require('lspconfig')
local luasnip = require('luasnip')

-- 1. SETUP THE COMPLETION ENGINE
cmp.setup({
  -- Snippet expansion is required for arguments to populate correctly
  snippet = {
    expand = function(args)
      luasnip.lsp_expand(args.body)
    end,
  },

  -- Window styling for the suggestion box and documentation float
  window = {
    completion = cmp.config.window.bordered(),
    documentation = cmp.config.window.bordered(), 
  },

  -- Key mappings
  mapping = cmp.mapping.preset.insert({
    ['<C-b>'] = cmp.mapping.scroll_docs(-4),
    ['<C-f>'] = cmp.mapping.scroll_docs(4),
    ['<C-Space>'] = cmp.mapping.complete(), -- Force trigger completion
    ['<CR>'] = cmp.mapping.confirm({ select = true }), -- Accept suggestion
  }),

  -- Sources: 'nvim_lsp' is what provides the intelligent 'self' data
  sources = cmp.config.sources({
    { name = 'nvim_lsp' }, 
    { name = 'luasnip' },
    { name = 'buffer' },
  }),
  
  -- formatting: This adds the "Method", "Field", "Text" icons
  formatting = {
    format = function(entry, vim_item)
      vim_item.menu = ({
        nvim_lsp = "[LSP]",
        luasnip = "[Snippet]",
        buffer = "[Buffer]",
      })[entry.source.name]
      return vim_item
    end
  },
})

-- 2. SETUP ZIG LANGUAGE SERVER (ZLS)
-- This captures the capabilities of nvim-cmp to send to ZLS
local capabilities = require('cmp_nvim_lsp').default_capabilities()

lspconfig.zls.setup({
  capabilities = capabilities,
  
  -- ZLS Specific Settings to ensure you get arguments and details
  settings = {
    zls = {
      enable_snippets = true,              -- Auto-fill arguments
      enable_argument_placeholders = true, -- Placeholders like (a: i32, b: bool)
      highlight_global_var_declarations = true,
      operator_completions = true,
      include_at_in_builtins = true,       -- Suggest @import, @cImport
    },
  },
})