package pds

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"atcr.io/pkg/atproto"
	"github.com/bluesky-social/indigo/repo"
	"github.com/ipfs/go-cid"
)

// AddCrewMember adds a new crew member to the hold and commits to carstore
// Uses deterministic rkey based on member DID hash for O(1) lookups and automatic deduplication
// If the member already exists, updates their record (upsert behavior)
func (p *HoldPDS) AddCrewMember(ctx context.Context, memberDID, role string, permissions []string) (cid.Cid, error) {
	crewRecord := &atproto.CrewRecord{
		Type:        atproto.CrewCollection,
		Member:      memberDID,
		Role:        role,
		Permissions: permissions,
		AddedAt:     time.Now().Format(time.RFC3339),
	}

	// Use deterministic rkey based on member DID hash
	// UpsertRecord handles create-or-update automatically
	rkey := atproto.CrewRecordKey(memberDID)
	_, recordCID, _, err := p.repomgr.UpsertRecord(ctx, p.uid, atproto.CrewCollection, rkey, crewRecord)
	if err != nil {
		return cid.Undef, fmt.Errorf("failed to upsert crew record: %w", err)
	}

	return recordCID, nil
}

// GetCrewMember retrieves a crew member by their record key
func (p *HoldPDS) GetCrewMember(ctx context.Context, rkey string) (cid.Cid, *atproto.CrewRecord, error) {
	// Use repomgr.GetRecord - our types are registered in init()
	recordCID, val, err := p.repomgr.GetRecord(ctx, p.uid, atproto.CrewCollection, rkey, cid.Undef)
	if err != nil {
		return cid.Undef, nil, fmt.Errorf("failed to get crew record: %w", err)
	}

	// Type assert to our concrete type
	crewRecord, ok := val.(*atproto.CrewRecord)
	if !ok {
		return cid.Undef, nil, fmt.Errorf("unexpected type for crew record: %T", val)
	}

	return recordCID, crewRecord, nil
}

// GetCrewMemberByDID retrieves a crew member by their DID using O(1) lookup
// Uses deterministic rkey based on member DID hash
func (p *HoldPDS) GetCrewMemberByDID(ctx context.Context, memberDID string) (cid.Cid, *atproto.CrewRecord, error) {
	rkey := atproto.CrewRecordKey(memberDID)
	return p.GetCrewMember(ctx, rkey)
}

// CrewMemberWithKey pairs a crew record with its rkey and CID
type CrewMemberWithKey struct {
	Rkey   string
	Cid    cid.Cid
	Record *atproto.CrewRecord
}

// ListCrewMembers returns all crew members with their rkeys
func (p *HoldPDS) ListCrewMembers(ctx context.Context) ([]*CrewMemberWithKey, error) {
	var crew []*CrewMemberWithKey

	// Create read-only session for ForEach access
	// repomgr doesn't expose ForEach, so we need direct repo access
	session, err := p.carstore.ReadOnlySession(p.uid)
	if err != nil {
		return nil, fmt.Errorf("failed to create read-only session: %w", err)
	}

	// Get repo head
	head, err := p.carstore.GetUserRepoHead(ctx, p.uid)
	if err != nil {
		return nil, fmt.Errorf("failed to get repo head: %w", err)
	}

	if !head.Defined() {
		return nil, fmt.Errorf("repo not initialized")
	}

	// Open repo
	r, err := repo.OpenRepo(ctx, session, head)
	if err != nil {
		return nil, fmt.Errorf("failed to open repo: %w", err)
	}

	// Iterate over all crew records
	err = r.ForEach(ctx, atproto.CrewCollection, func(k string, v cid.Cid) error {
		// Extract collection and rkey from full path (k is like "io.atcr.hold.crew/3m37dr2ddit22")
		parts := strings.Split(k, "/")
		if len(parts) < 2 {
			return nil // Skip invalid keys
		}

		// Extract actual collection and rkey
		actualCollection := strings.Join(parts[:len(parts)-1], "/")
		rkey := parts[len(parts)-1]

		// MST keys are sorted, so once we hit a different collection, stop walking
		if actualCollection != atproto.CrewCollection {
			return repo.ErrDoneIterating
		}

		// Get the record directly from the repo we already have open
		// (calling GetCrewMember would open a new session unnecessarily)
		recordCID, recBytes, err := r.GetRecordBytes(ctx, k)
		if err != nil {
			return fmt.Errorf("failed to get crew record: %w", err)
		}

		// Unmarshal the CBOR bytes into our concrete type
		var crewRecord atproto.CrewRecord
		if err := crewRecord.UnmarshalCBOR(bytes.NewReader(*recBytes)); err != nil {
			return fmt.Errorf("failed to decode crew record: %w", err)
		}

		crew = append(crew, &CrewMemberWithKey{
			Rkey:   rkey,
			Cid:    recordCID,
			Record: &crewRecord,
		})
		return nil
	})

	if err != nil {
		// ErrDoneIterating is expected when we stop walking early
		// Use errors.Is to handle wrapped errors (indigo wraps with %w in MST walk)
		if errors.Is(err, repo.ErrDoneIterating) {
			// Successfully stopped at collection boundary
		} else if strings.Contains(err.Error(), "not found") {
			// If the collection doesn't exist yet (empty repo or no records created),
			// return empty list instead of error
			return []*CrewMemberWithKey{}, nil
		} else {
			return nil, fmt.Errorf("failed to list crew members: %w", err)
		}
	}

	return crew, nil
}

// RemoveCrewMember removes a crew member by rkey
func (p *HoldPDS) RemoveCrewMember(ctx context.Context, rkey string) error {
	// Use repomgr.DeleteRecord - it will automatically commit!
	// This fixes the bug where deletions weren't being committed
	err := p.repomgr.DeleteRecord(ctx, p.uid, atproto.CrewCollection, rkey)
	if err != nil {
		return fmt.Errorf("failed to delete crew record: %w", err)
	}

	return nil
}

// RemoveCrewMemberByDID removes a crew member by their DID using O(1) lookup
func (p *HoldPDS) RemoveCrewMemberByDID(ctx context.Context, memberDID string) error {
	rkey := atproto.CrewRecordKey(memberDID)
	return p.RemoveCrewMember(ctx, rkey)
}

// UpdateCrewMemberTier updates a crew member's tier
// Uses O(1) lookup via hash-based rkey and PutRecord for atomic upsert
func (p *HoldPDS) UpdateCrewMemberTier(ctx context.Context, memberDID, tier string) error {
	// O(1) lookup using hash-based rkey
	_, existing, err := p.GetCrewMemberByDID(ctx, memberDID)
	if err != nil {
		return fmt.Errorf("crew member not found: %w", err)
	}

	// If tier is already the same, no update needed
	if existing.Tier == tier {
		return nil
	}

	// Create updated record (PutRecord handles upsert with same rkey)
	newRecord := &atproto.CrewRecord{
		Type:        atproto.CrewCollection,
		Member:      existing.Member,
		Role:        existing.Role,
		Permissions: existing.Permissions,
		Tier:        tier,
		Plankowner:  existing.Plankowner, // Preserve early adopter flag
		AddedAt:     existing.AddedAt,    // Preserve original add time
	}

	rkey := atproto.CrewRecordKey(memberDID)
	_, _, err = p.repomgr.PutRecord(ctx, p.uid, atproto.CrewCollection, rkey, newRecord)
	if err != nil {
		return fmt.Errorf("failed to update crew record: %w", err)
	}

	return nil
}

// TODO(crew-migration): Remove this migration code after all holds have been upgraded (added 2026-01-06)
// This migrates TID-based crew records to hash-based rkeys for O(1) lookups

// MigrateCrewRecordsToHashRkeys migrates old TID-based crew records to hash-based rkeys
// This is idempotent - records that already have hash-based rkeys are skipped
// Returns the number of records migrated
func (p *HoldPDS) MigrateCrewRecordsToHashRkeys(ctx context.Context) (int, error) {
	// List all crew members (includes both TID and hash-based rkeys)
	members, err := p.ListCrewMembers(ctx)
	if err != nil {
		return 0, fmt.Errorf("failed to list crew members: %w", err)
	}

	slog.Info("Starting crew record migration", "totalRecords", len(members))

	migrated := 0
	duplicatesDeleted := 0
	alreadyHashBased := 0
	seen := make(map[string]bool) // Track seen member DIDs to handle duplicates

	for _, m := range members {
		memberDID := m.Record.Member
		expectedRkey := atproto.CrewRecordKey(memberDID)

		// Skip if already using hash-based rkey
		if m.Rkey == expectedRkey {
			seen[memberDID] = true
			alreadyHashBased++
			continue
		}

		// This is a TID-based record that needs migration
		slog.Info("Migrating crew record to hash-based rkey",
			"memberDID", memberDID,
			"oldRkey", m.Rkey,
			"newRkey", expectedRkey)

		// Check if we already have a hash-based record for this DID (duplicate handling)
		if seen[memberDID] {
			// Already migrated this DID, just delete the old TID record
			slog.Info("Deleting duplicate TID-based crew record",
				"memberDID", memberDID,
				"rkey", m.Rkey)
			if err := p.RemoveCrewMember(ctx, m.Rkey); err != nil {
				slog.Warn("Failed to delete duplicate crew record",
					"rkey", m.Rkey,
					"error", err)
			} else {
				duplicatesDeleted++
			}
			continue
		}

		// Create new record with hash-based rkey (PutRecord handles upsert)
		newRecord := &atproto.CrewRecord{
			Type:        atproto.CrewCollection,
			Member:      m.Record.Member,
			Role:        m.Record.Role,
			Permissions: m.Record.Permissions,
			Tier:        m.Record.Tier,
			AddedAt:     m.Record.AddedAt,
		}

		_, _, err := p.repomgr.PutRecord(ctx, p.uid, atproto.CrewCollection, expectedRkey, newRecord)
		if err != nil {
			slog.Error("Failed to create hash-based crew record",
				"memberDID", memberDID,
				"error", err)
			continue
		}

		// Delete the old TID-based record
		if err := p.RemoveCrewMember(ctx, m.Rkey); err != nil {
			slog.Warn("Failed to delete old TID-based crew record",
				"rkey", m.Rkey,
				"error", err)
			// Continue anyway - the new record is created
		}

		seen[memberDID] = true
		migrated++
	}

	slog.Info("Crew record migration complete",
		"migrated", migrated,
		"duplicatesDeleted", duplicatesDeleted,
		"alreadyHashBased", alreadyHashBased,
		"totalRecords", len(members))

	return migrated, nil
}