package meshcli

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"strings"
	"sync"
	"testing"
	"time"
)

// controllerSays is a controller answering each request in turn from a script, and recording what it was asked.
type controllerSays struct {
	mu     sync.Mutex
	script []func(Asked) ([]byte, error)
	asked  []Asked
}

func (c *controllerSays) ask(_ context.Context, body []byte) ([]byte, error) {
	c.mu.Lock()
	defer c.mu.Unlock()
	var a Asked
	_ = json.Unmarshal(body, &a)
	c.asked = append(c.asked, a)
	if len(c.script) == 0 {
		return nil, context.DeadlineExceeded
	}
	next := c.script[0]
	if len(c.script) > 1 {
		c.script = c.script[1:]
	}
	return next(a)
}

func result(v any) func(Asked) ([]byte, error) {
	return func(Asked) ([]byte, error) { return json.Marshal(map[string]any{"result": v}) }
}

func fastFollow(t *testing.T) {
	was := followEvery
	followEvery = time.Millisecond
	t.Cleanup(func() { followEvery = was })
}

// A line still running when the controller first answers is followed, by its call, to what it printed.
func TestALineStillRunningIsFollowedToItsAnswer(t *testing.T) {
	fastFollow(t)
	running := result(map[string]any{"running": true, "call": "call-9"})
	c := &controllerSays{script: []func(Asked) ([]byte, error){running, running, running,
		result(map[string]any{"stdout": []byte("pushed\n"), "exit": 0, "terminal": true})}}
	a := AskTheController(context.Background(), c.ask, Asked{Line: []string{"push", "laptop"}, Account: "op", UID: 1000})
	if string(a.Stdout) != "pushed\n" || !a.Terminal || a.Refused != "" || a.Unknown != "" {
		t.Fatalf("followed to %+v", a)
	}
	for _, f := range c.asked[1:] {
		if f.Follow != "call-9" || f.Account != "op" || len(f.Line) != 0 {
			t.Fatalf("a follow asked %+v", f)
		}
	}
}

// **No answer in time is never "nothing ran"** (review of ADR 0272): the line was asked and may have run, and the
// call to look at is named when it is known.
func TestNoAnswerInTimeSaysTheLineMayHaveRun(t *testing.T) {
	fastFollow(t)
	c := &controllerSays{}
	a := AskTheController(context.Background(), c.ask, Asked{Line: []string{"push"}, Account: "op"})
	if a.Refused != "" || !strings.Contains(a.Unknown, "may have run") || a.Exit == 0 {
		t.Fatalf("a request with no answer reads %+v", a)
	}
	c = &controllerSays{script: []func(Asked) ([]byte, error){result(map[string]any{"running": true, "call": "call-3"}),
		func(Asked) ([]byte, error) { return nil, context.DeadlineExceeded }}}
	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
	defer cancel()
	a = AskTheController(ctx, c.ask, Asked{Line: []string{"push"}, Account: "op"})
	if a.Refused != "" || !strings.Contains(a.Unknown, "call-3") || !strings.Contains(a.Unknown, "may have run") {
		t.Fatalf("a running line never answered reads %+v", a)
	}
}

// A request the bus never carried to a controller ran nothing, and says so.
func TestARequestNobodyTookSaysNothingRan(t *testing.T) {
	c := &controllerSays{script: []func(Asked) ([]byte, error){func(Asked) ([]byte, error) {
		return nil, fmt.Errorf("%w: nothing on this machine answers mesh.control.laptop.cli", ErrNotAsked)
	}}}
	a := AskTheController(context.Background(), c.ask, Asked{Line: []string{"status"}, Account: "op"})
	if !strings.Contains(a.Refused, "nothing ran") || a.Unknown != "" {
		t.Fatalf("a request nobody took reads %+v", a)
	}
	c = &controllerSays{script: []func(Asked) ([]byte, error){func(Asked) ([]byte, error) {
		return nil, fmt.Errorf("%w: this machine has no link to the bus open now", ErrNotAsked)
	}}}
	if a := AskTheController(context.Background(), c.ask, Asked{Line: []string{"status"}}); !strings.Contains(a.Refused, "nothing ran") {
		t.Fatalf("no link reads %+v", a)
	}
}

// **Any error once the request may have been delivered is not known, never "nothing ran"** (review of ADR 0272):
// only a request the link says it never asked — no link open, nobody listening — ran nothing.
func TestOnlyARequestNeverAskedSaysNothingRan(t *testing.T) {
	for _, c := range []struct {
		err     error
		nothing bool
	}{
		{fmt.Errorf("%w: this machine has no link to the bus open now", ErrNotAsked), true},
		{fmt.Errorf("%w: nothing on this machine answers mesh.control.laptop.cli", ErrNotAsked), true},
		{errors.New("nats: connection closed"), false},
		{errors.New("mesh.control.laptop.cli: permissions violation"), false},
		{context.DeadlineExceeded, false},
	} {
		err := c.err
		ctl := &controllerSays{script: []func(Asked) ([]byte, error){func(Asked) ([]byte, error) { return nil, err }}}
		a := AskTheController(context.Background(), ctl.ask, Asked{Line: []string{"push"}, Account: "op"})
		if c.nothing && (!strings.Contains(a.Refused, "nothing ran") || a.Unknown != "") {
			t.Errorf("%v reads %+v; it was never asked", err, a)
		}
		if !c.nothing && (a.Refused != "" || !strings.Contains(a.Unknown, "may have run")) {
			t.Errorf("%v reads %+v; it may have been asked", err, a)
		}
	}
}