local function root_markers_with_field(root_files, new_names, field, fname)
    local path = vim.fn.fnamemodify(fname, ":h")
    local found = vim.fs.find(new_names, { path = path, upward = true })

    for _, f in ipairs(found or {}) do
        -- Match the given `field`.
        for line in io.lines(f) do
            if line:find(field) then
                root_files[#root_files + 1] = vim.fs.basename(f)
                break
            end
        end
    end

    return root_files
end

local function insert_package_json(root_files, field, fname)
    return root_markers_with_field(root_files, { "package.json", "package.json5" }, field, fname)
end

return {
    cmd = { "vscode-eslint-language-server", "--stdio" },
    filetypes = {
        "javascript",
        "javascriptreact",
        "javascript.jsx",
        "typescript",
        "typescriptreact",
        "typescript.tsx",
        "vue",
        "svelte",
        "astro",
        "htmlangular",
    },
    root_dir = function(bufnr, on_dir)
        local root_file_patterns = {
            ".eslintrc",
            ".eslintrc.js",
            ".eslintrc.cjs",
            ".eslintrc.yaml",
            ".eslintrc.yml",
            ".eslintrc.json",
            "eslint.config.js",
            "eslint.config.mjs",
            "eslint.config.cjs",
            "eslint.config.ts",
            "eslint.config.mts",
            "eslint.config.cts",
        }

        local fname = vim.api.nvim_buf_get_name(bufnr)
        root_file_patterns = insert_package_json(root_file_patterns, "eslintConfig", fname)
        on_dir(vim.fs.dirname(vim.fs.find(root_file_patterns, { path = fname, upward = true })[1]))
    end,
    workspace_required = true,
    settings = {
        validate = "on",
        packageManager = nil,
        useESLintClass = false,
        experimental = {
            useFlatConfig = false,
        },
        codeActionOnSave = {
            enable = false,
            mode = "all",
        },
        format = true,
        quiet = false,
        onIgnoredFiles = "off",
        rulesCustomizations = {},
        run = "onType",
        problems = {
            shortenToSingleLine = false,
        },
        -- nodePath configures the directory in which the eslint server should start its node_modules resolution.
        -- This path is relative to the workspace folder (root dir) of the server instance.
        nodePath = "",
        -- use the workspace folder location or the file location (if no workspace folder is open) as the working directory
        workingDirectory = { mode = "location" },
        codeAction = {
            disableRuleComment = {
                enable = true,
                location = "separateLine",
            },
            showDocumentation = {
                enable = true,
            },
        },
    },
    before_init = function(_, config)
        -- The "workspaceFolder" is a VSCode concept. It limits how far the
        -- server will traverse the file system when locating the ESLint config
        -- file (e.g., .eslintrc).
        local root_dir = config.root_dir

        if root_dir then
            config.settings = config.settings or {}
            config.settings.workspaceFolder = {
                uri = root_dir,
                name = vim.fn.fnamemodify(root_dir, ":t"),
            }

            -- Support flat config
            local flat_config_files = {
                "eslint.config.js",
                "eslint.config.mjs",
                "eslint.config.cjs",
                "eslint.config.ts",
                "eslint.config.mts",
                "eslint.config.cts",
            }

            for _, file in ipairs(flat_config_files) do
                if vim.fn.filereadable(root_dir .. "/" .. file) == 1 then
                    config.settings.experimental = config.settings.experimental or {}
                    config.settings.experimental.useFlatConfig = true
                    break
                end
            end

            -- Support Yarn2 (PnP) projects
            local pnp_cjs = root_dir .. "/.pnp.cjs"
            local pnp_js = root_dir .. "/.pnp.js"
            if vim.uv.fs_stat(pnp_cjs) or vim.uv.fs_stat(pnp_js) then
                local cmd = config.cmd
                config.cmd = vim.list_extend({ "yarn", "exec" }, cmd)
            end
        end
    end,
    handlers = {
        ["eslint/openDoc"] = function(_, result)
            if result then
                vim.ui.open(result.url)
            end
            return {}
        end,
        ["eslint/confirmESLintExecution"] = function(_, result)
            if not result then
                return
            end
            return 4 -- approved
        end,
        ["eslint/probeFailed"] = function()
            vim.notify("[lspconfig] ESLint probe failed.", vim.log.levels.WARN)
            return {}
        end,
        ["eslint/noLibrary"] = function()
            vim.notify("[lspconfig] Unable to find ESLint library.", vim.log.levels.WARN)
            return {}
        end,
    },
}