package keeper

import (
	"encoding/json"
	"fmt"

	storetypes "cosmossdk.io/store/types"
	"github.com/cosmos/cosmos-sdk/codec"
	sdk "github.com/cosmos/cosmos-sdk/types"

	"github.com/oy/openyield/x/partner/types"
)

// keeper.go holds the store-backed Keeper for the partner module's
// Anchor credential runtime (P3-02-01, REQ-035).
//
// The Keeper wraps an sdk.KVStore via a storeKey. It holds the
// AnchorCredential records (by anchor-id). The v0.3 in-memory registry
// Keeper stub (types.Keeper, x/partner/types/types.go) is RETAINED for
// the Partner registry (non-Anchor partners — the v0.3 skeleton); the
// v0.5 runtime promotes ONLY the Anchor credential lifecycle to a
// store-backed keeper (D-054 simtest grade). The Partner registry stays
// on the v0.3 in-memory stub (non-Anchor partner tiers are not promoted
// in v0.5 — out of scope; only the Anchor credential lifecycle is).
//
// The Keeper also holds the two expected-keeper shims (WatcherKeeper for
// 6-of-9 quorum authz on issue/revoke; HubKeeper for custody-provider-id
// validity on onboard — the P3→P4 hub dep edge broken by the interface
// shim per G-003 / ARCHITECTURE.md v0.5). The shims are interfaces
// (G-003 — no struct import of x/watcher/types or x/hub/types); the
// concrete keepers satisfy them structurally.
//
// State-machine ordering (vision §7, enforced in every handler):
//   ValidateBasic → keeper authz → state mutation → ctx.EventManager().EmitEvent

// Keeper is the store-backed partner Anchor-credential keeper.
type Keeper struct {
	cdc           codec.Codec
	storeKey      storetypes.StoreKey
	watcherKeeper types.WatcherKeeper
	hubKeeper     types.HubKeeper
}

// NewKeeper constructs a new store-backed partner Anchor-credential
// Keeper. The WatcherKeeper and HubKeeper expected-keeper shims are
// injected (nil-able for partial tests; the handlers guard nil shims
// and skip the corresponding authz/validity check, still mutating state
// — the simtest wiring document this). The HubKeeper shim is the P3→P4
// hub dep edge: in P3 simtest it is wired to a stub (G-003 test
// exemption); the real hub keeper is wired in P4.
func NewKeeper(cdc codec.Codec, storeKey storetypes.StoreKey, wk types.WatcherKeeper, hk types.HubKeeper) Keeper {
	return Keeper{
		cdc:           cdc,
		storeKey:      storeKey,
		watcherKeeper: wk,
		hubKeeper:     hk,
	}
}

// SetWatcherKeeper sets the WatcherKeeper expected-keeper shim (for
// post-construction wiring, e.g., app wiring or test setup).
func (k *Keeper) SetWatcherKeeper(wk types.WatcherKeeper) { k.watcherKeeper = wk }

// SetHubKeeper sets the HubKeeper expected-keeper shim (for
// post-construction wiring, e.g., app wiring or test setup). This is
// the P3→P4 hub dep edge: P4 wires the real hub keeper via this setter
// or via NewKeeper.
func (k *Keeper) SetHubKeeper(hk types.HubKeeper) { k.hubKeeper = hk }

// --- Anchor credential store -------------------------------------------------

var anchorKeyPrefix = []byte("anchor/")

func anchorKey(anchorID string) []byte {
	return append(anchorKeyPrefix, []byte(anchorID)...)
}

// GetAnchorCredential loads an AnchorCredential by anchor-id. Returns the
// credential and true if found, or zero value + false if not.
func (k Keeper) GetAnchorCredential(ctx sdk.Context, anchorID string) (types.AnchorCredential, bool) {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(anchorKey(anchorID))
	if bz == nil {
		return types.AnchorCredential{}, false
	}
	var c types.AnchorCredential
	if err := json.Unmarshal(bz, &c); err != nil {
		return types.AnchorCredential{}, false
	}
	return c, true
}

// SetAnchorCredential persists an AnchorCredential by anchor-id.
func (k Keeper) SetAnchorCredential(ctx sdk.Context, c types.AnchorCredential) {
	store := ctx.KVStore(k.storeKey)
	bz, err := json.Marshal(c)
	if err != nil {
		panic(fmt.Sprintf("partner: marshal anchor credential %q: %v", c.AnchorID, err))
	}
	store.Set(anchorKey(c.AnchorID), bz)
}

// AllAnchorCredentials returns all persisted AnchorCredential records
// (iteration helper).
func (k Keeper) AllAnchorCredentials(ctx sdk.Context) []types.AnchorCredential {
	store := ctx.KVStore(k.storeKey)
	iterator := store.Iterator(anchorKeyPrefix, prefixEnd(anchorKeyPrefix))
	defer iterator.Close()
	out := []types.AnchorCredential{}
	for ; iterator.Valid(); iterator.Next() {
		var c types.AnchorCredential
		if err := json.Unmarshal(iterator.Value(), &c); err == nil {
			out = append(out, c)
		}
	}
	return out
}

// prefixEnd returns the key that sorts immediately after all keys sharing
// the given prefix (the standard prefix-iteration end key: increment the
// last byte, drop overflow). Used for store.Iterator(start, prefixEnd(start))
// prefix scans.
func prefixEnd(prefix []byte) []byte {
	if len(prefix) == 0 {
		return nil
	}
	end := make([]byte, len(prefix))
	copy(end, prefix)
	for i := len(end) - 1; i >= 0; i-- {
		end[i]++
		if end[i] != 0 {
			return end
		}
	}
	// All bytes were 0xFF; return nil (iterate to end of store).
	return nil
}