-- https://github.com/golang/tools/tree/master/gopls

local mod_cache = nil

---@param fname string
---@return string?
local function get_root(fname)
    if mod_cache and fname:sub(1, #mod_cache) == mod_cache then
        local clients = vim.lsp.get_clients({ name = 'gopls' })
        if #clients > 0 then
            return clients[#clients].config.root_dir
        end
    end
    return vim.fs.root(fname, { 'go.work', 'go.mod', '.git' })
end

return {
    cmd = { 'gopls' },
    filetypes = { 'go', 'gomod', 'gowork', 'gotmpl' },
    root_dir = function(bufnr, on_dir)
        local fname = vim.api.nvim_buf_get_name(bufnr)
        -- see: https://github.com/neovim/nvim-lspconfig/issues/804
        if mod_cache then
            on_dir(get_root(fname))
            return
        end
        local cmd = { 'go', 'env', 'GOMODCACHE' }
        vim.system(cmd, { text = true }, function(output)
            if output.code == 0 then
                if output.stdout then
                    mod_cache = vim.trim(output.stdout)
                end
                on_dir(get_root(fname))
            else
                vim.notify(('[gopls] cmd failed with code %d: %s\n%s'):format(output.code, cmd, output.stderr))
            end
        end)
    end,
    settings = {
        gopls = {
            gofumpt = true,
            codelenses = {
                gc_details = false,
                generate = true,
                regenerate_cgo = true,
                run_govulncheck = true,
                test = true,
                tidy = true,
                upgrade_dependency = true,
                vendor = true,
            },
            hints = {
                assignVariableTypes = false,
                compositeLiteralFields = false,
                compositeLiteralTypes = true,
                constantValues = true,
                functionTypeParameters = false,
                parameterNames = false,
                rangeVariableTypes = true,
            },
            analyses = {
                fieldalignment = true,
                nilness = true,
                unusedparams = true,
                unusedwrite = true,
                useany = true,
            },
            usePlaceholders = false,
            completeUnimported = true,
            staticcheck = true,
            directoryFilters = { '-.git', '-.vscode', '-.idea', '-.vscode-test', '-node_modules' },
            semanticTokens = true,
        },
    },
    on_attach = function(client)
        -- workaround for gopls not supporting semanticTokensProvider
        -- https://github.com/golang/go/issues/54531#issuecomment-1464982242
        if not client.server_capabilities.semanticTokensProvider then
            local semantic = client.config.capabilities.textDocument.semanticTokens
            client.server_capabilities.semanticTokensProvider = {
                full = true,
                legend = {
                    tokenTypes = semantic.tokenTypes,
                    tokenModifiers = semantic.tokenModifiers,
                },
                range = true,
            }
        end
        -- end workaround
    end,
}