package batch

// P6 task 02: the runner's core — types, Submit (idempotency, caps, storage), Status, Touch and
// Cancel — with no workers yet: every job stays queued. The helpers here are shared with task
// 03's runner_test.go.

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"testing"
	"time"

	"git.wntrmute.dev/kyle/sift/internal/auth"
	"git.wntrmute.dev/kyle/sift/internal/dcache"
)

var (
	alice = &auth.Caller{Name: "alice", Workspace: "hermes-fleet"}
	bob   = &auth.Caller{Name: "bob", Workspace: "hermes-fleet"}
	carol = &auth.Caller{Name: "carol", Workspace: "hermes-fleet"}
)

func newRunner(t *testing.T, fetch FetchFunc, cfg Config) *Runner {
	t.Helper()
	db, err := dcache.Open("", 1<<20, slog.New(slog.NewTextHandler(io.Discard, nil)))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = db.Close() })
	r := New(db, fetch, cfg, slog.New(slog.NewTextHandler(io.Discard, nil)))
	t.Cleanup(r.Close) // runs before db.Close (cleanups are LIFO)
	return r
}

func waitStatus(t *testing.T, r *Runner, id, want string) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		j, _, ok := r.Status(id)
		if ok && j.Status == want {
			return
		}
		time.Sleep(2 * time.Millisecond)
	}
	j, _, _ := r.Status(id)
	t.Fatalf("job %s never reached %q (now %q)", id, want, j.Status)
}

func urls(ss ...string) []Target {
	var out []Target
	for _, s := range ss {
		out = append(out, Target{URL: "https://" + s + ".example/"})
	}
	return out
}

// Submit stores the job queued with its targets pending, before it returns.
func TestSubmitStoresQueued(t *testing.T) {
	r := newRunner(t, func(context.Context, *auth.Caller, Target) (Result, error) {
		return Result{Content: "ok"}, nil
	}, Config{Workers: 1})
	id, reused, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
	if err != nil || reused || len(id) != 32 {
		t.Fatalf("submit id=%q reused=%v err=%v, want a 32-hex-char id", id, reused, err)
	}
	j, ts, ok := r.Status(id)
	if !ok || j.ID != id || j.Caller != "alice" || j.TargetsTotal != 2 || j.CreatedAt == 0 {
		t.Fatalf("job %+v ok=%v", j, ok)
	}
	if j.Status != "queued" && j.Status != "running" && j.Status != "done" {
		t.Fatalf("status %q", j.Status)
	}
	if len(ts) != 2 || ts[0].Idx != 0 || ts[0].URL != "https://a.example/" || ts[1].URL != "https://b.example/" {
		t.Fatalf("targets %+v", ts)
	}
}

// Cancelling a job no worker has reached: it is cancelled at once, its targets stay pending,
// and the same list then starts a new job.
func TestCancelQueued(t *testing.T) {
	release := make(chan struct{})
	defer close(release)
	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
		<-release
		return Result{Content: "ok"}, nil
	}
	r := newRunner(t, fetch, Config{Workers: 1})
	busy, _, err := r.Submit(context.Background(), bob, dcache.ClassFleet, urls("x")) // occupies the only worker once there is one
	if err != nil {
		t.Fatal(err)
	}
	_ = busy
	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
	if err != nil {
		t.Fatal(err)
	}
	if !r.Cancel(id) {
		t.Fatal("cancel returned false")
	}
	j, ts, _ := r.Status(id)
	if j.Status != "cancelled" || ts[0].Status != "pending" || ts[1].Status != "pending" {
		t.Fatalf("after cancel: %+v %+v", j, ts)
	}
	if r.Cancel(id) || r.Cancel("no-such-job") {
		t.Fatal("cancel of a finished or unknown job must return false")
	}
	id2, reused, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
	if err != nil || reused || id2 == id {
		t.Fatalf("resubmit after cancel id=%q reused=%v err=%v", id2, reused, err)
	}
}

// Touch keeps a job alive; Status never does.
func TestTouchAndStatusLease(t *testing.T) {
	db, err := dcache.Open("", 1<<20, slog.New(slog.NewTextHandler(io.Discard, nil)))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = db.Close() })
	release := make(chan struct{})
	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
		<-release
		return Result{Content: "ok"}, nil
	}
	r := New(db, fetch, Config{Workers: 1}, slog.New(slog.NewTextHandler(io.Discard, nil)))
	t.Cleanup(r.Close)
	defer close(release) // runs before the cleanups
	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a"))
	if err != nil {
		t.Fatal(err)
	}
	time.Sleep(50 * time.Millisecond) // let a worker (task 03) take the target; it then blocks
	before, _ := db.BatchJob(id)
	time.Sleep(1100 * time.Millisecond) // the lease is in whole seconds
	r.Status(id)
	if j, _ := db.BatchJob(id); j.Lease != before.Lease {
		t.Fatalf("Status moved the lease %d → %d; a read must not write", before.Lease, j.Lease)
	}
	r.Touch(id)
	if j, _ := db.BatchJob(id); j.Lease <= before.Lease {
		t.Fatalf("Touch did not move the lease: %d → %d", before.Lease, j.Lease)
	}
}

func TestCaps(t *testing.T) {
	release := make(chan struct{})
	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
		<-release
		return Result{Content: "ok"}, nil
	}
	r := newRunner(t, fetch, Config{TargetsPerJob: 2, JobsTotal: 2})
	defer close(release)
	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b", "c")); !errors.Is(err, ErrTooManyTargets) {
		t.Fatalf("3 targets over a cap of 2: want ErrTooManyTargets, got %v", err)
	}
	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, nil); !errors.Is(err, ErrNoTargets) {
		t.Fatalf("no targets: want ErrNoTargets, got %v", err)
	}
	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a")); err != nil {
		t.Fatal(err)
	}
	// alice's job is live (queued or running): a second, different list is refused.
	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("z")); !errors.Is(err, ErrCallerBusy) {
		t.Fatalf("want ErrCallerBusy, got %v", err)
	}
	if _, _, err := r.Submit(context.Background(), bob, dcache.ClassFleet, urls("b")); err != nil {
		t.Fatal(err)
	}
	// Two live jobs in total: a third caller is refused.
	if _, _, err := r.Submit(context.Background(), carol, dcache.ClassFleet, urls("c")); !errors.Is(err, ErrBusy) {
		t.Fatalf("want ErrBusy, got %v", err)
	}
}

func TestStatusUnknown(t *testing.T) {
	r := newRunner(t, func(context.Context, *auth.Caller, Target) (Result, error) { return Result{}, nil }, Config{})
	if _, _, ok := r.Status("no-such-job"); ok {
		t.Fatal("unknown id must be ok=false")
	}
}