-- keymaps
local on_attach = function(client, bufnr)
    local function buf_set_keymap(...)
        vim.api.nvim_buf_set_keymap(bufnr, ...)
    end
    local function buf_set_option(...)
        vim.api.nvim_buf_set_option(bufnr, ...)
    end

    buf_set_option('omnifunc', 'v:lua.vim.lsp.omnifunc')

    -- Mappings.
    local opts = {noremap = true, silent = true}
    buf_set_keymap('n', 'gD', '<Cmd>lua vim.lsp.buf.declaration()<CR>', opts)
    buf_set_keymap('n', 'gd', '<Cmd>lua vim.lsp.buf.definition()<CR>', opts)
    buf_set_keymap('n', 'K', '<Cmd>lua vim.lsp.buf.hover()<CR>', opts)
    buf_set_keymap('n', 'gi', '<cmd>lua vim.lsp.buf.implementation()<CR>', opts)
    buf_set_keymap('n', '<C-k>', '<cmd>lua vim.lsp.buf.signature_help()<CR>',
                   opts)
    buf_set_keymap('n', '<space>wa',
                   '<cmd>lua vim.lsp.buf.add_workspace_folder()<CR>', opts)
    buf_set_keymap('n', '<space>wr',
                   '<cmd>lua vim.lsp.buf.remove_workspace_folder()<CR>', opts)
    buf_set_keymap('n', '<space>wl',
                   '<cmd>lua print(vim.inspect(vim.lsp.buf.list_workspace_folders()))<CR>',
                   opts)
    buf_set_keymap('n', '<space>D',
                   '<cmd>lua vim.lsp.buf.type_definition()<CR>', opts)
    buf_set_keymap('n', '<space>rn', '<cmd>lua vim.lsp.buf.rename()<CR>', opts)
    buf_set_keymap('n', 'gr', '<cmd>lua vim.lsp.buf.references()<CR>', opts)
    buf_set_keymap('n', '<space>e',
                   '<cmd>lua vim.lsp.diagnostic.show_line_diagnostics()<CR>',
                   opts)
    buf_set_keymap('n', '[d', '<cmd>lua vim.lsp.diagnostic.goto_prev()<CR>',
                   opts)
    buf_set_keymap('n', ']d', '<cmd>lua vim.lsp.diagnostic.goto_next()<CR>',
                   opts)
    buf_set_keymap('n', '<space>q',
                   '<cmd>lua vim.lsp.diagnostic.set_loclist()<CR>', opts)

    -- Set some keybinds conditional on server capabilities
    if client.resolved_capabilities.document_formatting then
        buf_set_keymap("n", "<space>f", "<cmd>lua vim.lsp.buf.formatting()<CR>",
                       opts)
    elseif client.resolved_capabilities.document_range_formatting then
        buf_set_keymap("n", "<space>f",
                       "<cmd>lua vim.lsp.buf.range_formatting()<CR>", opts)
    end

    -- Set autocommands conditional on server_capabilities
    if client.resolved_capabilities.document_highlight then
        vim.api.nvim_exec([[
    augroup lsp_document_highlight
    autocmd! * <buffer>
    autocmd CursorHold <buffer> lua vim.lsp.buf.document_highlight()
    autocmd CursorMoved <buffer> lua vim.lsp.buf.clear_references()
    augroup END
    ]], false)
    end
end

-- Configure lua language server for neovim development
local lua_settings = {
    Lua = {
        runtime = {
            -- LuaJIT in the case of Neovim
            version = 'LuaJIT',
            path = vim.split(package.path, ';')
        },
        diagnostics = {
            -- Get the language server to recognize the `vim` global
            globals = {'vim'}
        },
        workspace = {
            -- Make the server aware of Neovim runtime files
            library = {
                [vim.fn.expand('$VIMRUNTIME/lua')] = true,
                [vim.fn.expand('$VIMRUNTIME/lua/vim/lsp')] = true
            }
        }
    }
}

-- config that activates keymaps and enables snippet support
local function make_config()
    local capabilities = vim.lsp.protocol.make_client_capabilities()
    capabilities.textDocument.completion.completionItem.snippetSupport = true
    return {
        -- enable snippet support
        capabilities = capabilities,
        -- map buffer local keybindings when the language server attaches
        on_attach = on_attach
    }
end

-- lsp-install
local function setup_servers()
    require'lspinstall'.setup()

    -- get all installed servers
    local servers = require'lspinstall'.installed_servers()

    for _, server in pairs(servers) do
        local config = make_config()

        -- language specific config
        if server == "lua" then config.settings = lua_settings end

        require'lspconfig'[server].setup(config)

    end
end

setup_servers()

-- Automatically reload after `:LspInstall <server>` so we don't have to restart neovim
require'lspinstall'.post_install_hook = function()
    setup_servers() -- reload installed servers
    vim.cmd("bufdo e") -- this triggers the FileType autocmd that starts the server
end