Autogenerated documentation: using LSP make call hierarchy graphs

[joonas-fi]

package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"log/slog"
	"os/exec"

	"github.com/sourcegraph/jsonrpc2"
	lsp "github.com/toitware/go-lsp"
	"github.com/toitware/go-lsp/lspext"
)

// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/

type CallHierarchyItem struct {
	Name           string          `json:"name"`
	Kind           int             `json:"kind"`
	Tags           []int           `json:"tags,omitempty"`
	Detail         string          `json:"detail,omitempty"`
	URI            lsp.DocumentURI `json:"uri"`
	Range          lsp.Range       `json:"range"`
	SelectionRange lsp.Range       `json:"selectionRange"`
	Data           interface{}     `json:"data,omitempty"`
}

type CallHierarchyPrepareParams struct {
	lsp.TextDocumentPositionParams

	WorkDoneToken interface{} `json:"workDoneToken,omitempty"`
}

type CallHierarchyIncomingCall struct {
	From       CallHierarchyItem `json:"from"`
	FromRanges []lsp.Range       `json:"fromRanges"`
}

type CallHierarchyOutgoingCall struct {
	To         CallHierarchyItem `json:"to"`
	FromRanges []lsp.Range       `json:"fromRanges"`
}

// Minimal stream wrapper for jsonrpc2
type stdioStream struct {
	io.Reader
	io.Writer
	io.Closer
}

var _ interface {
	io.Reader
	io.Writer
	io.Closer
} = (*stdioStream)(nil)

func hailait() {
	ctx := context.Background()

	// Start gopls in stdio mode
	cmd := exec.Command("bob", "tools", "langserver")
	stdin, _ := cmd.StdinPipe()
	stdout, _ := cmd.StdoutPipe()
	cmd.Stderr = cmd.Stdout

	if err := cmd.Start(); err != nil {
		log.Fatal("failed to start gopls:", err)
	}

	stream := jsonrpc2.NewBufferedStream(&stdioStream{stdout, stdin, stdin}, jsonrpc2.VSCodeObjectCodec{})
	conn := jsonrpc2.NewConn(ctx, stream, jsonrpc2.HandlerWithError(func(ctx context.Context, c *jsonrpc2.Conn, r *jsonrpc2.Request) (result interface{}, err error) {
		switch r.Method {
		case "window/showMessage":
			logMessageParams := struct {
				Message string `json:"message"`
				Type    int    `json:"type"`
			}{}
			if err := json.Unmarshal(*r.Params, &logMessageParams); err != nil {
				panic(err)
			}
			slog.Info("LSP server", "kind", "show", "msg", logMessageParams.Message, "type", logMessageParams.Type)
			return nil, nil
		case "window/logMessage":
			logMessageParams := struct {
				Message string `json:"message"`
				Type    int    `json:"type"`
			}{}
			if err := json.Unmarshal(*r.Params, &logMessageParams); err != nil {
				panic(err)
			}
			slog.Info("LSP server", "kind", "log", "msg", logMessageParams.Message, "type", logMessageParams.Type)
			return nil, nil
		default:
			slog.Warn("returning error", "request", r.Method, "params", string(*r.Params))
			return nil, errors.New("requests not implemented")
		}
	}))
	defer stream.Close()

	// ---- Initialize ----
	initReq := lsp.InitializeParams{
		RootURI: "file:///workspace",
	}

	var initResp lsp.InitializeResult
	if err := conn.Call(ctx, "initialize", initReq, &initResp); err != nil {
		log.Fatal("initialize error:", err)
	}

	// Tell server we're ready
	_ = conn.Notify(ctx, "initialized", struct{}{})

	// --- Prepare call hierarchy ---
	params := CallHierarchyPrepareParams{
		TextDocumentPositionParams: lsp.TextDocumentPositionParams{
			TextDocument: lsp.TextDocumentIdentifier{
				URI: initReq.RootURI + "/pkg/mypkg/example.go",
			},
			Position: lsp.Position{ // -1 because positions are 0-based
				Line:      114 - 1,
				Character: 6 - 1,
			},
		},
	}

	var items []CallHierarchyItem
	if err := conn.Call(ctx, "textDocument/prepareCallHierarchy", params, &items); err != nil {
		log.Fatal("prepareCallHierarchy:", err)
	}

	if len(items) == 0 {
		log.Println("No call hierarchy items found at location")
		return
	}

	item := items[0]
	fmt.Println("Item:", item.Name)

	_ = lspext.CacheSetParams{}
	// --- Incoming calls ---
	var incoming []CallHierarchyIncomingCall
	if err := conn.Call(ctx, "callHierarchy/incomingCalls", struct {
		Item CallHierarchyItem `json:"item"`
	}{item}, &incoming); err != nil {
		log.Fatal("incomingCalls: ", err)
	}

	fmt.Println("\nIncoming calls:")
	for _, c := range incoming {
		fmt.Println("   from:", c.From.Name)
	}

	// --- Outgoing calls ---
	// var outgoing []CallHierarchyOutgoingCall
	// if err := conn.Call(ctx, "callHierarchy/outgoingCalls", item, &outgoing); err != nil {
	// 	log.Fatal("outgoingCalls:", err)
	// }

	// fmt.Println("\nOutgoing calls:")
	// for _, c := range outgoing {
	// 	fmt.Println("   to:", c.To.Name)
	// }
}

go.mod:

	github.com/sourcegraph/jsonrpc2 v0.2.1 // indirect
	github.com/toitware/go-lsp v0.0.0-20240220075859-6b0ca01316f0 // indirect