package integration

import (
	"context"
	"errors"
	"os"
	"path/filepath"
	"sync"
	"testing"
	"time"

	"strings"

	"orchestra/internal/domain"
	"orchestra/internal/herdr"
	"orchestra/internal/human"
	"orchestra/internal/orchestrator"
	"orchestra/internal/router"
	"orchestra/internal/store"
)

// trace records the real order of operations across the launch path, which is
// the property under test: reconciliation must be upstream of the agent, not
// merely present somewhere in the process.
type trace struct {
	mu    sync.Mutex
	steps []string
}

func (tr *trace) add(step string) {
	tr.mu.Lock()
	tr.steps = append(tr.steps, step)
	tr.mu.Unlock()
}

func (tr *trace) snapshot() []string {
	tr.mu.Lock()
	defer tr.mu.Unlock()
	return append([]string(nil), tr.steps...)
}

type tracingSource struct {
	tr     *trace
	inputs []human.Input
	next   string
	err    error
}

func (s *tracingSource) FetchAfter(_ context.Context, task domain.Task, cursor store.SourceCursor) ([]human.Input, store.SourceCursor, error) {
	s.tr.add("fetch")
	if s.err != nil {
		return nil, store.SourceCursor{}, s.err
	}
	return s.inputs, store.SourceCursor{TaskID: task.ID, Provider: "gitea", Cursor: s.next}, nil
}

// The milestone test: a comment written while the task was queued is durable
// and standing before the agent that will act on it is started.
func TestHumanInputReconciledBeforeAgentStarts(t *testing.T) {
	s, reg, _ := setup(t)
	task := ingest(t, s, "381")
	tr := &trace{}
	src := &tracingSource{tr: tr, next: "918", inputs: []human.Input{
		{Provider: "gitea", ExternalID: "918", Author: "kami", Body: "no, use b"},
	}}
	rec := &human.Reconciler{Store: s, Sources: map[string]human.Source{"gitea": src}}
	s.PreLease = func(id string) error { return rec.Reconcile(context.Background(), id) }

	c := &orchestrator.Coordinator{Store: s, Worktrees: worktrees{}, Adapters: adapters{&harness{}}, StatePath: t.TempDir() + "/sessions.json"}
	rt := router.Router{Store: s, Registry: reg, Reachability: alwaysReachable{}, OnLease: func(e domain.Event) error {
		tr.add("agent.start")
		return c.Start(context.Background(), e)
	}}
	leased, err := rt.AssignPending()
	if err != nil || len(leased) != 1 {
		t.Fatalf("leased=%d err=%v", len(leased), err)
	}

	if got := tr.snapshot(); len(got) != 2 || got[0] != "fetch" || got[1] != "agent.start" {
		t.Fatalf("order = %v, want fetch before agent.start", got)
	}
	intent, err := s.EffectiveIntent(task.ID)
	if err != nil {
		t.Fatal(err)
	}
	if len(intent.Decisions) != 1 || intent.Decisions[0].Value != "no, use b" {
		t.Fatalf("standing set = %+v", intent.Decisions)
	}
	if c, ok := s.SourceCursor(task.ID, "gitea"); !ok || c.Cursor != "918" {
		t.Fatalf("cursor = %+v ok=%v", c, ok)
	}
}

// Fail closed. If Orchestra cannot establish whether newer human input
// exists, no lease is minted, so nothing downstream can start an agent from
// the older intent.
func TestUnreachableSourceRefusesTheLease(t *testing.T) {
	s, reg, _ := setup(t)
	task := ingest(t, s, "381")
	tr := &trace{}
	src := &tracingSource{tr: tr, err: errors.New("gitea unreachable")}
	rec := &human.Reconciler{Store: s, Sources: map[string]human.Source{"gitea": src}}
	s.PreLease = func(id string) error { return rec.Reconcile(context.Background(), id) }

	h := &harness{}
	c := &orchestrator.Coordinator{Store: s, Worktrees: worktrees{}, Adapters: adapters{h}, StatePath: t.TempDir() + "/sessions.json"}
	rt := router.Router{Store: s, Registry: reg, Reachability: alwaysReachable{}, OnLease: func(e domain.Event) error {
		tr.add("agent.start")
		return c.Start(context.Background(), e)
	}}
	leased, err := rt.AssignPending()
	if len(leased) != 0 {
		t.Fatalf("a lease was minted despite unreachable human input: %v (err=%v)", leased, err)
	}
	for _, step := range tr.snapshot() {
		if step == "agent.start" {
			t.Fatal("an agent was started without reconciliation")
		}
	}
	got, _ := s.Task(task.ID)
	if got.State != domain.StateQueued {
		t.Fatalf("task state = %s, want queued so a later attempt retries", got.State)
	}
	if got.Lease != nil {
		t.Fatal("task must not hold a lease")
	}
}

// The successor case: a comment arriving after session 1 released must be
// standing before session 2 is leased, not merged in later.
func TestSuccessorLeaseReconcilesBeforeResume(t *testing.T) {
	s, reg, _ := setup(t)
	task := ingest(t, s, "381")
	tr := &trace{}
	src := &tracingSource{tr: tr}
	rec := &human.Reconciler{Store: s, Sources: map[string]human.Source{"gitea": src}}
	s.PreLease = func(id string) error { return rec.Reconcile(context.Background(), id) }

	if _, err := s.Lease(task.ID, "h1", 30*time.Minute); err != nil {
		t.Fatal(err)
	}
	ref, err := s.PutArtifact([]byte("handoff: next, implement a"))
	if err != nil {
		t.Fatal(err)
	}
	leasedTask, _ := s.Task(task.ID)
	if err := s.Append(domain.Event{ID: domain.NewID(), Type: "TaskReleased", TaskID: task.ID, Version: leasedTask.Version + 1, Surface: "system", Payload: mustJSON(map[string]any{
		"handoff_ref":      ref,
		"anchor_sha":       "0123456789012345678901234567890123456789",
		"harness_id":       leasedTask.Lease.HarnessID,
		"lease_epoch":      leasedTask.Lease.Epoch,
		"expected_version": leasedTask.Version,
	})}); err != nil {
		t.Fatal(err)
	}

	// The human comments while the task sits queued between sessions.
	src.inputs = []human.Input{{Provider: "gitea", ExternalID: "918", Author: "kami", Body: "no, use b"}}
	src.next = "918"

	rt := router.Router{Store: s, Registry: reg, Reachability: alwaysReachable{}, OnLease: func(e domain.Event) error {
		intent, err := s.EffectiveIntent(e.TaskID)
		if err != nil {
			return err
		}
		// Read at the moment ownership begins: the successor's authority must
		// already contain the correction, before it reads any handoff.
		if len(intent.Decisions) != 1 || intent.Decisions[0].Value != "no, use b" {
			t.Errorf("successor launched with standing set %+v", intent.Decisions)
		}
		if intent.Task.HandoffRef != ref {
			t.Errorf("handoff ref = %q, want %q", intent.Task.HandoffRef, ref)
		}
		return nil
	}}
	leased, err := rt.AssignPending()
	if err != nil || len(leased) != 1 {
		t.Fatalf("leased=%d err=%v", len(leased), err)
	}
}

// capturingAdapter records the exact launch instruction the agent receives.
type capturingAdapter struct {
	*harness
	mu     sync.Mutex
	prompt string
}

func (a *capturingAdapter) LeasePrompt(_ context.Context, _, worktree, prompt string) (herdr.Session, error) {
	a.mu.Lock()
	a.prompt = prompt
	a.mu.Unlock()
	return herdr.Session{Harness: "h1", PaneID: "pane-1", Worktree: worktree}, nil
}

type capturingAdapters struct{ a herdr.Adapter }

func (c capturingAdapters) Adapter(string) (herdr.Adapter, error) { return c.a, nil }

// The live proof: the contract says implement a, the human says use b, and the
// agent's launch instruction presents b as authority.
func TestAgentLaunchInstructionCarriesTheCorrection(t *testing.T) {
	s, reg, _ := setup(t)
	task := ingest(t, s, "381")
	amend, _ := s.Task(task.ID)
	if err := s.Append(domain.Event{ID: domain.NewID(), Type: "TaskAmended", TaskID: task.ID, Version: amend.Version + 1, Surface: "system", Payload: mustJSON(map[string]any{
		"description": "implement a",
	})}); err != nil {
		t.Fatal(err)
	}

	src := &tracingSource{tr: &trace{}, next: "918", inputs: []human.Input{
		{Provider: "gitea", ExternalID: "918", Author: "kami", Body: "no, use b"},
	}}
	rec := &human.Reconciler{Store: s, Sources: map[string]human.Source{"gitea": src}}
	s.PreLease = func(id string) error { return rec.Reconcile(context.Background(), id) }

	a := &capturingAdapter{harness: &harness{}}
	c := &orchestrator.Coordinator{Store: s, Worktrees: worktrees{}, Adapters: capturingAdapters{a}, StatePath: t.TempDir() + "/sessions.json"}
	rt := router.Router{Store: s, Registry: reg, Reachability: alwaysReachable{}, OnLease: func(e domain.Event) error {
		return c.Start(context.Background(), e)
	}}
	if leased, err := rt.AssignPending(); err != nil || len(leased) != 1 {
		t.Fatalf("leased=%d err=%v", len(leased), err)
	}

	a.mu.Lock()
	prompt := a.prompt
	a.mu.Unlock()
	if prompt == "" {
		t.Fatal("no launch instruction was sent")
	}
	decision := strings.Index(prompt, "no, use b")
	goal := strings.Index(prompt, "implement a")
	if decision < 0 || goal < 0 {
		t.Fatalf("prompt missing goal or decision:\n%s", prompt)
	}
	if !strings.Contains(prompt, "## Current human decisions") {
		t.Fatalf("prompt has no decisions section:\n%s", prompt)
	}
	if !strings.Contains(prompt, "Authority order") {
		t.Fatalf("prompt does not state the authority order:\n%s", prompt)
	}
	if goal > decision {
		t.Fatal("goal must precede the decisions section")
	}
}

// tempWorktrees gives one test its own worktree, so what a launch writes into
// it can be read back.
type tempWorktrees struct{ path string }

func (w tempWorktrees) Create(context.Context, domain.Task) (string, error) { return w.path, nil }

// Burn-in depends on this: the exact instruction a session was launched with is
// on disk, not only in pane scrollback the harness has reflowed.
func TestLaunchWritesTheContextItSent(t *testing.T) {
	s, reg, _ := setup(t)
	task := ingest(t, s, "381")
	src := &tracingSource{tr: &trace{}, next: "918", inputs: []human.Input{
		{Provider: "gitea", ExternalID: "918", Author: "kami", Body: "no, use b"},
	}}
	rec := &human.Reconciler{Store: s, Sources: map[string]human.Source{"gitea": src}}
	s.PreLease = func(id string) error { return rec.Reconcile(context.Background(), id) }

	worktree := t.TempDir()
	a := &capturingAdapter{harness: &harness{}}
	c := &orchestrator.Coordinator{Store: s, Worktrees: tempWorktrees{path: worktree}, Adapters: capturingAdapters{a}, StatePath: t.TempDir() + "/sessions.json"}
	rt := router.Router{Store: s, Registry: reg, Reachability: alwaysReachable{}, OnLease: func(e domain.Event) error {
		return c.Start(context.Background(), e)
	}}
	if leased, err := rt.AssignPending(); err != nil || len(leased) != 1 {
		t.Fatalf("leased=%d err=%v", len(leased), err)
	}

	b, err := os.ReadFile(filepath.Join(worktree, herdr.LaunchContextFile))
	if err != nil {
		t.Fatalf("no launch context recorded for task %s: %v", task.ID, err)
	}
	a.mu.Lock()
	sent := a.prompt
	a.mu.Unlock()
	if string(b) != sent {
		t.Fatalf("recorded context differs from what was sent:\nrecorded:\n%s\nsent:\n%s", b, sent)
	}
	if !strings.Contains(string(b), "no, use b") {
		t.Fatalf("recorded context missing the standing decision:\n%s", b)
	}
}