---@brief
---
--- https://github.com/denoland/deno
---
--- Deno's built-in language server
---
--- To appropriately highlight codefences returned from denols, you will need to augment vim.g.markdown_fenced languages
---  in your init.lua. Example:
---
--- ```lua
--- vim.g.markdown_fenced_languages = {
---   "ts=typescript"
--- }
--- ```

local lsp = vim.lsp

local function virtual_text_document_handler(uri, res, client)
    if not res then
        return nil
    end

    local lines = vim.split(res.result, "\n")
    local bufnr = vim.uri_to_bufnr(uri)

    local current_buf = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
    if #current_buf ~= 0 then
        return nil
    end

    vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, lines)
    vim.api.nvim_set_option_value("readonly", true, { buf = bufnr })
    vim.api.nvim_set_option_value("modified", false, { buf = bufnr })
    vim.api.nvim_set_option_value("modifiable", false, { buf = bufnr })
    lsp.buf_attach_client(bufnr, client.id)
end

local function virtual_text_document(uri, client)
    local params = {
        textDocument = {
            uri = uri,
        },
    }
    local result = client:request_sync("deno/virtualTextDocument", params)
    virtual_text_document_handler(uri, result, client)
end

local function denols_handler(err, result, ctx, config)
    if not result or vim.tbl_isempty(result) then
        return nil
    end

    local client = vim.lsp.get_client_by_id(ctx.client_id)
    for _, res in pairs(result) do
        local uri = res.uri or res.targetUri
        if uri:match("^deno:") then
            virtual_text_document(uri, client)
            res["uri"] = uri
            res["targetUri"] = uri
        end
    end

    lsp.handlers[ctx.method](err, result, ctx, config)
end

---@type vim.lsp.Config
return {
    cmd = { require("monaqa.lsp").mason_bin("deno"), "lsp" },
    cmd_env = { NO_COLOR = true },
    filetypes = {
        "javascript",
        "javascriptreact",
        "javascript.jsx",
        "typescript",
        "typescriptreact",
        "typescript.tsx",
    },
    root_markers = { "deno.json", "deno.jsonc", ".git" },
    settings = {
        deno = {
            enable = true,
            suggest = {
                imports = {
                    hosts = {
                        ["https://deno.land"] = true,
                    },
                },
            },
        },
    },
    handlers = {
        ["textDocument/definition"] = denols_handler,
        ["textDocument/typeDefinition"] = denols_handler,
        ["textDocument/references"] = denols_handler,
    },
    on_attach = function(client, bufnr)
        vim.api.nvim_buf_create_user_command(bufnr, "LspDenolsCache", function()
            client:exec_cmd({
                command = "deno.cache",
                arguments = { {}, vim.uri_from_bufnr(bufnr) },
            }, { bufnr = bufnr }, function(err, _, ctx)
                if err then
                    local uri = ctx.params.arguments[2]
                    vim.notify("cache command failed for" .. vim.uri_to_fname(uri), vim.log.levels.ERROR)
                end
            end)
        end, {
            desc = "Cache a module and all of its dependencies.",
        })
    end,
}