package stdio

import (
	"bufio"
	"encoding/json"
	"io"
	"strings"
	"testing"
	"time"
)

// A Go bundle keeps and watches its state through the runtime (novox/hq ADR 0201): the watch's
// current values are handled before it returns, its changes are named by the watch's id, a change for
// no watch of this bundle is refused, and put, get and keys are asked of the runtime as the module.
func TestABundleKeepsAndWatchesStateThroughTheRuntime(t *testing.T) {
	t.Setenv(ServedAs, "keeper")
	inR, inW := io.Pipe()
	outR, outW := io.Pipe()
	seen := make(chan string, 16)
	watched := make(chan error, 1)
	go func() {
		_ = ServeOn("", []Tool{
			{Name: "start", Run: func(map[string]any) (any, error) {
				go func() {
					watched <- State("servers").Watch("", func(c StateChange) error {
						seen <- c.Op + " " + c.Key + " " + string(c.Value)
						return nil
					})
				}()
				return "started", nil
			}},
			{Name: "remember", Run: func(a map[string]any) (any, error) {
				return State("servers").Put(a["key"].(string), a["value"])
			}},
			{Name: "recall", Run: func(a map[string]any) (any, error) { return State("servers").Get(a["key"].(string)) }},
		}, inR, outW)
	}()
	lines := bufio.NewScanner(outR)
	next := func() map[string]any {
		done := make(chan map[string]any, 1)
		go func() {
			if lines.Scan() {
				var m map[string]any
				_ = json.Unmarshal(lines.Bytes(), &m)
				done <- m
			}
		}()
		select {
		case m := <-done:
			return m
		case <-time.After(3 * time.Second):
			t.Fatal("the bundle said nothing")
			return nil
		}
	}
	send := func(m map[string]any) { b, _ := json.Marshal(m); _, _ = inW.Write(append(b, '\n')) }

	send(map[string]any{"jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": map[string]any{"name": "start"}})
	got := map[string]map[string]any{}
	for len(got) < 2 {
		m := next()
		if m["method"] != nil {
			got[m["method"].(string)] = m
		} else {
			got["answer"] = m
		}
	}
	watch := got["mesh/state.watch"]
	if p := watch["params"].(map[string]any); p["state"] != "servers" || p["key"] != "" {
		t.Fatalf("asked to watch %v", p)
	}
	// The current value, for this watch, before the watch is answered.
	send(map[string]any{"jsonrpc": "2.0", "id": 50, "method": "mesh/state", "params": map[string]any{"watch": watch["id"],
		"change": map[string]any{"state": "servers", "key": "all.one", "op": "put", "value": map[string]any{"url": "http://one"}, "current": true}}})
	if r := next(); r["id"] != float64(50) || r["error"] != nil {
		t.Fatalf("a current value was answered %v", r)
	}
	if s := <-seen; s != `put all.one {"url":"http://one"}` {
		t.Fatalf("handled %q", s)
	}
	select {
	case err := <-watched:
		t.Fatalf("the watch returned before it was answered: %v", err)
	default:
	}
	send(map[string]any{"jsonrpc": "2.0", "id": watch["id"], "result": map[string]any{}})
	if err := <-watched; err != nil {
		t.Fatal(err)
	}
	// A change for a watch this bundle never asked for is refused.
	send(map[string]any{"jsonrpc": "2.0", "id": 51, "method": "mesh/state", "params": map[string]any{"watch": "bundle-999",
		"change": map[string]any{"key": "x", "op": "put"}}})
	if r := next(); r["id"] != float64(51) || !strings.Contains(r["error"].(map[string]any)["message"].(string), "names no watch") {
		t.Fatalf("a change for no watch was answered %v", r)
	}

	// Put: asked of the runtime as the module, the revision is the tool's answer.
	send(map[string]any{"jsonrpc": "2.0", "id": 2, "method": "tools/call", "params": map[string]any{"name": "remember",
		"arguments": map[string]any{"key": "all.two", "value": map[string]any{"url": "http://two"}}}})
	put := next()
	if put["method"] != "mesh/state.put" || put["params"].(map[string]any)["key"] != "all.two" || put["params"].(map[string]any)["state"] != "servers" {
		t.Fatalf("asked %v", put)
	}
	send(map[string]any{"jsonrpc": "2.0", "id": put["id"], "result": map[string]any{"revision": 9}})
	if r := next(); r["id"] != float64(2) || r["result"].(map[string]any)["content"].([]any)[0].(map[string]any)["text"] != "9" {
		t.Fatalf("the put answered %v", r)
	}
	// Get of a key with no value is nil.
	send(map[string]any{"jsonrpc": "2.0", "id": 3, "method": "tools/call", "params": map[string]any{"name": "recall",
		"arguments": map[string]any{"key": "nothing"}}})
	get := next()
	send(map[string]any{"jsonrpc": "2.0", "id": get["id"], "result": nil})
	if r := next(); r["id"] != float64(3) || r["result"].(map[string]any)["content"].([]any)[0].(map[string]any)["text"] != "null" {
		t.Fatalf("the get answered %v", r)
	}
	_ = inW.Close()
}