local M = {}

local function default_attach(client, bufnr)
    require('completion').on_attach()

    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', '<leader>wa', '<cmd>lua vim.lsp.buf.add_workspace_folder()<CR>', opts)
    buf_set_keymap('n', '<leader>wr', '<cmd>lua vim.lsp.buf.remove_workspace_folder()<CR>', opts)
    buf_set_keymap('n', '<leader>wl', '<cmd>lua print(vim.inspect(vim.lsp.buf.list_workspace_folders()))<CR>', opts)
    buf_set_keymap('n', '<leader>D', '<cmd>lua vim.lsp.buf.type_definition()<CR>', opts)
    buf_set_keymap('n', '<leader>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', '<leader>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', '<leader>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", "<leader>f", "<cmd>lua vim.lsp.buf.formatting()<CR>", opts)
        vim.cmd([[
            augroup lsp_format
                autocmd!
                " autocmd BufWritePre *.rs,*.go lua vim.lsp.buf.formatting_sync(nil, 1000)
                autocmd BufWritePre <buffer> lua vim.lsp.buf.formatting_sync(nil, 1000)
            augroup END
        ]])
    elseif client.resolved_capabilities.document_range_formatting then
        buf_set_keymap("n", "<leader>f", "<cmd>lua vim.lsp.buf.formatting()<CR>", opts)
    end

    -- Set autocommands conditional on server_capabilities
    if client.resolved_capabilities.document_highlight then
        vim.cmd([[
        :hi LspReferenceRead cterm=bold ctermbg=red guibg=LightYellow
        :hi LspReferenceText cterm=bold ctermbg=red guibg=LightYellow
        :hi LspReferenceWrite cterm=bold ctermbg=red guibg=LightYellow
        augroup lsp_document_highlight
        autocmd!
            autocmd CursorHold <buffer> lua vim.lsp.buf.document_highlight()
            autocmd CursorMoved <buffer> lua vim.lsp.buf.clear_references()
        augroup END
        ]])
    end

    -- Some override telescope bindings
    buf_set_keymap("n", "<leader>t", "<cmd>Telescope lsp_document_symbols<CR>", opts)
    buf_set_keymap("n", "<leader>ft", "<cmd>Telescope lsp_dynamic_workspace_symbols<CR>", opts)
end

function M.config_lsp()
    local language_servers = {
        "bashls",
        "gopls",
        "pylsp",
        "rust_analyzer",
    }
    local lsp_config = require("lspconfig")

    for _, ls in ipairs(language_servers) do
        lsp_config[ls].setup{
            on_attach=default_attach,
            settings={
                pylsp={
                    configurationSources = {"flake8"},
                    formatCommand = {"black"},
                },
            },
        }
    end
end

return M