package state

import (
	"context"
	"strconv"
	"time"

	"github.com/kamadopool/kamado-api/internal/logmon"
	"github.com/kamadopool/kamado-api/internal/store"
)

// BlockRecord is a found block, merged from a logmon event with bitcoind
// data if available. Hash and Reward are populated best-effort via the
// RPC lookup scheduled right after the log line is seen; the reconcile
// loop fills any holes later. OrphanedAt is set if a periodic chain
// check finds the recorded hash no longer matches the canonical block
// at this height (i.e. the network reorged us out).
type BlockRecord struct {
	Height     int64     `json:"height"`
	Hash       string    `json:"hash,omitempty"`
	RewardBT   float64   `json:"reward_btc,omitempty"`
	FoundAt    time.Time `json:"found_at"`
	Source     string    `json:"source"` // "logmon" for now; "zmq" later
	ShareDiff  float64   `json:"share_diff,omitempty"`
	OrphanedAt time.Time `json:"orphaned_at,omitempty"`
}

// IngestAttemptEvents counts "Possible/Submitting block solve" log
// lines so we can compare attempts vs confirmations in the snapshot.
// A growing gap means bitcoind is rejecting our submissions or the
// RPC is failing. Persists the running counter so it survives restarts.
func (a *Aggregator) IngestAttemptEvents(ctx context.Context, events <-chan logmon.AttemptEvent) {
	for {
		select {
		case <-ctx.Done():
			return
		case ev, ok := <-events:
			if !ok {
				return
			}
			a.mu.Lock()
			a.blockSubmitAttempts++
			n := a.blockSubmitAttempts
			save := a.Store != nil && time.Since(a.lastSubmitCountSave) >= 30*time.Second
			if save {
				a.lastSubmitCountSave = time.Now()
			}
			a.mu.Unlock()
			a.Log.Info("logmon: submit attempt", "share_diff", ev.ShareDiff, "attempts", n)
			if save {
				if err := a.Store.SetKV(kvSubmitAttempts, strconv.FormatInt(n, 10)); err != nil {
					a.Log.Warn("submit attempts persist failed", "err", err)
				}
			}
		}
	}
}

// IngestBlockEvents reads block events from the tailer and appends them
// to the snapshot's block history. Runs until ctx is cancelled.
func (a *Aggregator) IngestBlockEvents(ctx context.Context, events <-chan logmon.BlockEvent) {
	for {
		select {
		case <-ctx.Done():
			return
		case ev, ok := <-events:
			if !ok {
				return
			}
			rec := BlockRecord{
				Height:    ev.Height,
				FoundAt:   ev.SeenAt,
				Source:    "logmon",
				ShareDiff: ev.ShareDiff,
			}
			// Best-effort enrich with hash + coinbase reward via bitcoind.
			// We look up the hash from height, then fetch the full block
			// (verbosity 2) to sum the coinbase outputs. Both are fire-
			// and-forget — if bitcoind is down we still record the block
			// with whatever we have.
			if a.RPC != nil {
				lookupCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
				if hash, err := a.RPC.GetBlockHash(lookupCtx, ev.Height); err == nil {
					rec.Hash = hash
					if blk, err := a.RPC.GetBlock(lookupCtx, hash); err == nil {
						rec.RewardBT = blk.CoinbaseReward()
					} else {
						a.Log.Warn("bitcoind getblock failed", "hash", hash, "err", err)
					}
				} else {
					a.Log.Warn("bitcoind getblockhash failed", "height", ev.Height, "err", err)
				}
				cancel()
			}
			isNew := true
			if a.Store != nil {
				inserted, err := a.Store.InsertBlock(store.Block{
					Height:    rec.Height,
					Hash:      rec.Hash,
					RewardBT:  rec.RewardBT,
					FoundAt:   rec.FoundAt,
					Source:    rec.Source,
					ShareDiff: rec.ShareDiff,
				})
				if err != nil {
					a.Log.Warn("block persist failed", "height", rec.Height, "err", err)
				} else if !inserted {
					a.Log.Warn("block at this height already recorded — duplicate or pre-existing entry, not counting as new",
						"height", rec.Height, "hash", rec.Hash)
					isNew = false
				}
			}
			if !isNew {
				continue
			}
			a.mu.Lock()
			a.blockSubmitsConfirmed++
			confirmed := a.blockSubmitsConfirmed
			a.mu.Unlock()
			if a.Store != nil {
				if err := a.Store.SetKV(kvSubmitsConfirmed, strconv.FormatInt(confirmed, 10)); err != nil {
					a.Log.Warn("confirmed count persist failed", "err", err)
				}
			}
			pushed := a.appendBlock(rec)
			a.Log.Info("block recorded", "height", rec.Height, "hash", rec.Hash, "confirmed", confirmed)
			// Push immediately so WebSocket clients see the solve
			// without waiting for the next poll tick.
			if a.OnRefresh != nil {
				a.OnRefresh(pushed)
			}
		}
	}
}

// ReconcileBlocks runs until ctx is cancelled, periodically:
//   1. Filling in missing hash/reward for blocks where the initial RPC
//      lookup failed (bitcoind hadn't indexed yet, or was down).
//   2. Comparing each non-orphaned hash against the canonical block at
//      its height; a mismatch means the network reorged us out and we
//      mark the row orphaned so the UI can render it accordingly.
// Both checks are bounded to the last reconcileLookback, so the cost
// stays constant regardless of total history size.
func (a *Aggregator) ReconcileBlocks(ctx context.Context) {
	if a.Store == nil || a.RPC == nil {
		return
	}
	t := time.NewTicker(reconcileInterval)
	defer t.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-t.C:
			a.reconcileOnce(ctx)
		}
	}
}

func (a *Aggregator) reconcileOnce(ctx context.Context) {
	since := time.Now().Add(-reconcileLookback)

	// Pass 1: enrichment. Fetch hash + reward for any missing-data rows.
	missing, err := a.Store.BlocksNeedingEnrichment(since)
	if err != nil {
		a.Log.Warn("reconcile: load missing failed", "err", err)
	}
	enrichedAny := false
	for _, b := range missing {
		lookupCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
		hash := b.Hash
		reward := b.RewardBT
		if hash == "" {
			if h, herr := a.RPC.GetBlockHash(lookupCtx, b.Height); herr == nil {
				hash = h
			} else {
				cancel()
				continue
			}
		}
		if reward == 0 && hash != "" {
			if blk, berr := a.RPC.GetBlock(lookupCtx, hash); berr == nil {
				reward = blk.CoinbaseReward()
			}
		}
		cancel()
		if hash != b.Hash || reward != b.RewardBT {
			if err := a.Store.UpdateEnrichment(b.Height, hash, reward); err != nil {
				a.Log.Warn("reconcile: update enrichment failed", "height", b.Height, "err", err)
				continue
			}
			a.Log.Info("reconcile: enriched block", "height", b.Height, "hash", hash, "reward", reward)
			enrichedAny = true
		}
	}

	// Pass 2: reorg detection. For non-orphaned blocks within the
	// lookback, confirm the canonical hash at that height still
	// matches our record. Don't bother with rows that are already
	// orphaned — we won't un-orphan, since the network already
	// chose another chain.
	recent, err := a.Store.Recent(64)
	if err != nil {
		a.Log.Warn("reconcile: load recent failed", "err", err)
		return
	}
	orphanedAny := false
	now := time.Now()
	for _, b := range recent {
		if b.Hash == "" || !b.OrphanedAt.IsZero() {
			continue
		}
		if b.FoundAt.Before(since) {
			continue
		}
		lookupCtx, cancel := context.WithTimeout(ctx, 3*time.Second)
		canonical, herr := a.RPC.GetBlockHash(lookupCtx, b.Height)
		cancel()
		if herr != nil {
			// Most likely cause: our bitcoind doesn't have this
			// height yet (index lag). Try again next sweep — don't
			// orphan on a transient RPC error.
			continue
		}
		if canonical != b.Hash {
			if err := a.Store.MarkOrphaned(b.Height, now); err != nil {
				a.Log.Warn("reconcile: mark orphaned failed", "height", b.Height, "err", err)
				continue
			}
			a.Log.Warn("reconcile: block orphaned by reorg",
				"height", b.Height, "ours", b.Hash, "canonical", canonical)
			orphanedAny = true
		}
	}

	if enrichedAny || orphanedAny {
		// Refresh the in-memory ring so the snapshot picks up the
		// changes immediately rather than waiting for the next poll.
		a.loadPersistedBlocks()
		a.mu.RLock()
		snap := a.snap
		a.mu.RUnlock()
		if a.OnRefresh != nil && len(snap.RecentBlocks) > 0 {
			a.OnRefresh(snap)
		}
	}
}

// maxBlockHistory caps in-memory block history. Persistence comes in
// Phase 2b.5 via SQLite; for now recent blocks survive only this
// process's lifetime.
const maxBlockHistory = 256

// appendBlock records a new block and returns a copy of the current
// snapshot with the updated history attached, suitable for an immediate
// WebSocket broadcast.
func (a *Aggregator) appendBlock(rec BlockRecord) Snapshot {
	a.mu.Lock()
	defer a.mu.Unlock()
	a.blocks = append(a.blocks, rec)
	if len(a.blocks) > maxBlockHistory {
		a.blocks = a.blocks[len(a.blocks)-maxBlockHistory:]
	}
	snap := a.snap
	snap.RecentBlocks = make([]BlockRecord, len(a.blocks))
	copy(snap.RecentBlocks, a.blocks)
	a.snap = snap
	return snap
}

// loadPersistedBlocks seeds a.blocks from the store so history survives
// restarts. Safe to call with a nil Store — becomes a no-op.
func (a *Aggregator) loadPersistedBlocks() {
	if a.Store == nil {
		return
	}
	rows, err := a.Store.Recent(maxBlockHistory)
	if err != nil {
		a.Log.Warn("block history load failed", "err", err)
		return
	}
	// Store returns newest-first; a.blocks is newest-last.
	recs := make([]BlockRecord, 0, len(rows))
	for i := len(rows) - 1; i >= 0; i-- {
		r := rows[i]
		recs = append(recs, BlockRecord{
			Height:     r.Height,
			Hash:       r.Hash,
			RewardBT:   r.RewardBT,
			FoundAt:    r.FoundAt,
			Source:     r.Source,
			ShareDiff:  r.ShareDiff,
			OrphanedAt: r.OrphanedAt,
		})
	}
	a.mu.Lock()
	a.blocks = recs
	// Surface refreshed history into the live snapshot so /api/snapshot
	// reflects the latest store state without waiting for the next
	// refresh tick (used by the reconcile loop).
	if a.snap.GeneratedAt.IsZero() {
		a.mu.Unlock()
		a.Log.Info("block history loaded", "count", len(recs))
		return
	}
	snap := a.snap
	if len(recs) > 0 {
		snap.RecentBlocks = make([]BlockRecord, len(recs))
		copy(snap.RecentBlocks, recs)
	} else {
		snap.RecentBlocks = nil
	}
	a.snap = snap
	a.mu.Unlock()
	a.Log.Info("block history loaded", "count", len(recs))
}

// Blocks returns a copy of the recent block history, newest last.
func (a *Aggregator) Blocks() []BlockRecord {
	a.mu.RLock()
	defer a.mu.RUnlock()
	out := make([]BlockRecord, len(a.blocks))
	copy(out, a.blocks)
	return out
}