package dispatcher

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

	"forge.secuaas.ovh/olivier/claude-failover/internal/config"
	"forge.secuaas.ovh/olivier/claude-failover/internal/delegation"
	"forge.secuaas.ovh/olivier/claude-failover/internal/router"
	"forge.secuaas.ovh/olivier/claude-failover/internal/secutools"
	"forge.secuaas.ovh/olivier/claude-failover/internal/state"
)

// fakeSecutools is a minimal stub used for routing tests. It records every
// SubmitJob call so tests can assert on the number/contents of submissions.
type fakeSecutools struct {
	mu       sync.Mutex
	submits  []*secutools.JobRequest
	statuses map[string]string
	results  map[string]*secutools.JobResult
	nextID   int
}

func newFakeSecutools() *fakeSecutools {
	return &fakeSecutools{
		statuses: make(map[string]string),
		results:  make(map[string]*secutools.JobResult),
	}
}

func (f *fakeSecutools) SubmitJob(_ context.Context, req *secutools.JobRequest) (*secutools.JobResponse, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.submits = append(f.submits, req)
	f.nextID++
	id := "job-" + itoa(f.nextID)
	f.statuses[id] = "pending"
	return &secutools.JobResponse{JobID: id, Status: "pending"}, nil
}

func (f *fakeSecutools) GetJob(_ context.Context, id string) (*secutools.JobStatus, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	st, ok := f.statuses[id]
	if !ok {
		return nil, errors.New("unknown")
	}
	return &secutools.JobStatus{JobID: id, Status: st}, nil
}

func (f *fakeSecutools) WaitForResult(_ context.Context, id string, _ time.Duration) (*secutools.JobResult, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	if r, ok := f.results[id]; ok {
		return r, nil
	}
	return nil, errors.New("no result")
}

// (uses itoa from dispatcher.go)

func setupTaskFile(t *testing.T, frontmatter, body string) (projectDir, inbox, taskPath string) {
	t.Helper()
	projectDir = t.TempDir()
	inbox = filepath.Join(projectDir, ".agent-queue", "inbox")
	if err := os.MkdirAll(inbox, 0755); err != nil {
		t.Fatal(err)
	}
	content := "---\n" + frontmatter + "\n---\n" + body
	taskPath = filepath.Join(inbox, "task-routing.md")
	if err := os.WriteFile(taskPath, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}
	return projectDir, inbox, taskPath
}

// TestRouteTask_ParsesNewFrontmatterFields ensures the dispatcher actually
// reads the new preferred_ai/allow_delegation/needs_claude_code fields.
func TestRouteTask_ParsesNewFrontmatterFields(t *testing.T) {
	_, _, taskPath := setupTaskFile(t,
		"title: Demo\npreferred_ai: gpu\nallow_delegation: true\ncomplexity_hint: low",
		"Body of task.")

	d := &Dispatcher{logger: log.Default()}
	dec, body, err := d.routeTask(taskPath)
	if err != nil {
		t.Fatal(err)
	}
	if dec.Provider != router.ProviderGPU {
		t.Errorf("expected ProviderGPU, got %v (%s)", dec.Provider, dec.Reason)
	}
	if body != "Body of task." {
		t.Errorf("body parsed wrong: %q", body)
	}
}

// TestDispatchProject_DelegatesGPUTask: a task with allow_delegation=true
// and preferred_ai=gpu must be sent to secutools and never reach a tmux
// session, even when one is available.
func TestDispatchProject_DelegatesGPUTask(t *testing.T) {
	projectDir, inbox, taskPath := setupTaskFile(t,
		"title: Delegated\npreferred_ai: gpu\nallow_delegation: true",
		"Analyze something.")

	tc := newMockTmux()
	tc.sessions["pool-0"] = true
	tc.paneOutput["pool-0"] = "❯ "

	s := state.New("")
	s.SetIdle("pool-0")

	fc := newFakeSecutools()
	mgr := delegation.New(fc, time.Millisecond)

	d := &Dispatcher{
		tmux:  tc,
		state: s,
		config: &config.Config{
			Pool: config.PoolConfig{
				Autonomous: config.AutonomousConfig{Prefix: "pool-", Max: 1},
			},
		},
		logger:     log.Default(),
		delegation: mgr,
	}

	d.dispatchProject(inbox)

	if len(fc.submits) != 1 {
		t.Fatalf("expected 1 SubmitJob call, got %d", len(fc.submits))
	}
	if fc.submits[0].PreferredAI != "gpu" {
		t.Errorf("expected preferred_ai=gpu, got %q", fc.submits[0].PreferredAI)
	}
	// .delegated marker is present, original .md kept (the reaper finalises later).
	if _, err := os.Stat(taskPath + ".delegated"); err != nil {
		t.Errorf("expected .delegated marker, got %v", err)
	}
	if _, err := os.Stat(taskPath); err != nil {
		t.Errorf("expected original .md to remain until reaped, got %v", err)
	}
	// pool-0 must remain idle (we did NOT launch a Claude Code agent).
	if st := s.GetSession("pool-0"); st == nil || st.State != "idle" {
		t.Errorf("expected pool-0 to stay idle, got %v", st)
	}
	_ = projectDir
}

// TestDispatchProject_LegacyTaskKeepsClaudeCode: backward-compat. A task
// with no new fields (or allow_delegation=false implicit) MUST go to a
// local Claude Code session.
func TestDispatchProject_LegacyTaskKeepsClaudeCode(t *testing.T) {
	_, inbox, taskPath := setupTaskFile(t,
		"title: Legacy\npriority: default",
		"Do classic work.")

	tc := newMockTmux()
	tc.sessions["pool-0"] = true
	tc.paneOutput["pool-0"] = "❯ "

	s := state.New("")
	s.SetIdle("pool-0")

	fc := newFakeSecutools()
	mgr := delegation.New(fc, time.Millisecond)

	d := &Dispatcher{
		tmux:  tc,
		state: s,
		config: &config.Config{
			Pool: config.PoolConfig{
				Autonomous: config.AutonomousConfig{Prefix: "pool-", Max: 1},
			},
		},
		logger:     log.Default(),
		delegation: mgr,
	}

	d.dispatchProject(inbox)

	if len(fc.submits) != 0 {
		t.Errorf("legacy task must NOT delegate, got %d submits", len(fc.submits))
	}
	// .dispatched marker present, session is working.
	if _, err := os.Stat(taskPath + ".dispatched"); err != nil {
		t.Errorf("expected .dispatched marker for Claude Code path, got %v", err)
	}
	if st := s.GetSession("pool-0"); st == nil || st.State != "working" {
		t.Errorf("expected pool-0 working, got %v", st)
	}
}

// TestDispatchProject_NeedsClaudeCodeBypassesDelegation: even with
// allow_delegation=true, needs_claude_code: true forces local execution.
func TestDispatchProject_NeedsClaudeCodeBypassesDelegation(t *testing.T) {
	_, inbox, _ := setupTaskFile(t,
		"title: Bypass\npreferred_ai: gpu\nallow_delegation: true\nneeds_claude_code: true",
		"This needs a real Claude session.")

	tc := newMockTmux()
	tc.sessions["pool-0"] = true
	tc.paneOutput["pool-0"] = "❯ "

	s := state.New("")
	s.SetIdle("pool-0")

	fc := newFakeSecutools()
	mgr := delegation.New(fc, time.Millisecond)

	d := &Dispatcher{
		tmux:  tc,
		state: s,
		config: &config.Config{
			Pool: config.PoolConfig{
				Autonomous: config.AutonomousConfig{Prefix: "pool-", Max: 1},
			},
		},
		logger:     log.Default(),
		delegation: mgr,
	}

	d.dispatchProject(inbox)

	if len(fc.submits) != 0 {
		t.Errorf("needs_claude_code must skip delegation, got %d submits", len(fc.submits))
	}
}

// TestEndToEnd_DelegationFlow: full happy path from inbox → submit →
// reaper → done/, with the dispatcher and delegation manager wired up.
func TestEndToEnd_DelegationFlow(t *testing.T) {
	projectDir, inbox, taskPath := setupTaskFile(t,
		"title: E2E\npreferred_ai: auto\nallow_delegation: true",
		"Summarize this.")

	tc := newMockTmux()
	s := state.New("")

	fc := newFakeSecutools()
	mgr := delegation.New(fc, time.Millisecond)

	d := &Dispatcher{
		tmux:   tc,
		state:  s,
		config: &config.Config{Pool: config.PoolConfig{Autonomous: config.AutonomousConfig{Max: 0}}},
		logger: log.Default(),
		delegation: mgr,
	}

	// 1. Dispatch — submits to fakeSecutools.
	d.dispatchProject(inbox)
	if len(fc.submits) != 1 {
		t.Fatalf("expected 1 submit, got %d", len(fc.submits))
	}
	jobID := "job-1"

	// 2. Backend completes the job.
	fc.mu.Lock()
	fc.statuses[jobID] = "completed"
	fc.results[jobID] = &secutools.JobResult{
		JobID: jobID, Response: "Summary", Provider: "gpu", Model: "qwen", CostCAD: 0.001,
	}
	fc.mu.Unlock()

	// 3. Reaper picks it up. mgr.Run drives reapOnce on each ticker tick;
	//    interval was set to 1ms in newDelegationManager so a 200ms
	//    context yields many cycles.
	mgr.SetLogger(log.Default())
	delegationReapNow(t, mgr, jobID)

	donePath := filepath.Join(projectDir, ".agent-queue", "done", "task-routing.md")
	body, err := os.ReadFile(donePath)
	if err != nil {
		t.Fatalf("missing done/ file: %v", err)
	}
	if !contains(string(body), "Summary") || !contains(string(body), "provider: gpu") {
		t.Errorf("done body missing expected fields:\n%s", body)
	}

	// Marker and original .md gone.
	if _, err := os.Stat(taskPath + ".delegated"); !os.IsNotExist(err) {
		t.Error("delegated marker should be removed")
	}
	if _, err := os.Stat(taskPath); !os.IsNotExist(err) {
		t.Error("original .md should be removed")
	}
}

// delegationReapNow drives one reap cycle of mgr by calling its public
// API. We need this because reapOnce is unexported in the delegation
// package. The Run loop ticker is too slow for tests, so we expose a
// trivial ticker-equivalent: temporarily run with an immediate context.
func delegationReapNow(t *testing.T, mgr *delegation.Manager, _ string) {
	t.Helper()
	ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
	defer cancel()
	// Run the manager briefly; the ticker fires after `interval` (1ms in
	// these tests) so within 200ms we get many reap cycles.
	mgr.Run(ctx)
}

func contains(s, sub string) bool {
	if sub == "" {
		return true
	}
	for i := 0; i+len(sub) <= len(s); i++ {
		if s[i:i+len(sub)] == sub {
			return true
		}
	}
	return false
}