---@brief
---
--- https://github.com/rust-lang/rust-analyzer
---
--- rust-analyzer (aka rls 2.0), a language server for Rust
---
---
--- See [docs](https://rust-analyzer.github.io/book/configuration.html) for extra settings. The settings can be used like this:
--- ```lua
--- vim.lsp.config('rust_analyzer', {
---   settings = {
---     ['rust-analyzer'] = {
---       diagnostics = {
---         enable = false;
---       }
---     }
---   }
--- })
--- ```
---
--- Note: do not set `init_options` for this LS config, it will be automatically populated by the contents of settings["rust-analyzer"] per
--- https://github.com/rust-lang/rust-analyzer/blob/eb5da56d839ae0a9e9f50774fa3eb78eb0964550/docs/dev/lsp-extensions.md?plain=1#L26.

local function reload_workspace(bufnr)
    local clients = vim.lsp.get_clients { bufnr = bufnr, name = "rust_analyzer" }
    for _, client in ipairs(clients) do
        vim.notify("Reloading Cargo Workspace")
        ---@diagnostic disable-next-line:param-type-mismatch
        client:request("rust-analyzer/reloadWorkspace", nil, function(err)
            if err then
                error(tostring(err))
            end
            vim.notify("Cargo workspace reloaded")
        end, 0)
    end
end

local function is_library(fname)
    local user_home = vim.fs.normalize(vim.env.HOME)
    local cargo_home = os.getenv("CARGO_HOME") or user_home .. "/.cargo"
    local registry = cargo_home .. "/registry/src"
    local git_registry = cargo_home .. "/git/checkouts"

    local rustup_home = os.getenv("RUSTUP_HOME") or user_home .. "/.rustup"
    local toolchains = rustup_home .. "/toolchains"

    for _, item in ipairs { toolchains, registry, git_registry } do
        if vim.fs.relpath(item, fname) then
            local clients = vim.lsp.get_clients { name = "rust_analyzer" }
            return #clients > 0 and clients[#clients].config.root_dir or nil
        end
    end
end

---@type vim.lsp.Config
return {
    cmd = { require("monaqa.lsp").mason_bin("rust-analyzer") },
    filetypes = { "rust" },
    root_dir = function(bufnr, on_dir)
        local fname = vim.api.nvim_buf_get_name(bufnr)
        local reused_dir = is_library(fname)
        if reused_dir then
            on_dir(reused_dir)
            return
        end

        local cargo_crate_dir = vim.fs.root(fname, { "Cargo.toml" })
        local cargo_workspace_root

        if cargo_crate_dir == nil then
            on_dir(
                vim.fs.root(fname, { "rust-project.json" })
                    or vim.fs.dirname(vim.fs.find(".git", { path = fname, upward = true })[1])
            )
            return
        end

        local cmd = {
            "cargo",
            "metadata",
            "--no-deps",
            "--format-version",
            "1",
            "--manifest-path",
            cargo_crate_dir .. "/Cargo.toml",
        }

        vim.system(cmd, { text = true }, function(output)
            if output.code == 0 then
                if output.stdout then
                    local result = vim.json.decode(output.stdout)
                    if result["workspace_root"] then
                        cargo_workspace_root = vim.fs.normalize(result["workspace_root"])
                    end
                end

                on_dir(cargo_workspace_root or cargo_crate_dir)
            else
                vim.schedule(function()
                    vim.notify(
                        ("[rust_analyzer] cmd failed with code %d: %s\n%s"):format(output.code, cmd, output.stderr)
                    )
                end)
            end
        end)
    end,
    capabilities = {
        experimental = {
            serverStatusNotification = true,
        },
    },
    before_init = function(init_params, config)
        -- See https://github.com/rust-lang/rust-analyzer/blob/eb5da56d839ae0a9e9f50774fa3eb78eb0964550/docs/dev/lsp-extensions.md?plain=1#L26
        if config.settings and config.settings["rust-analyzer"] then
            init_params.initializationOptions = config.settings["rust-analyzer"]
        end
    end,
    on_attach = function(_, bufnr)
        vim.api.nvim_buf_create_user_command(bufnr, "LspCargoReload", function()
            reload_workspace(bufnr)
        end, { desc = "Reload current cargo workspace" })
    end,
}