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/exit/types"
)

// keeper.go holds the store-backed Keeper for the exit module (P1-05-01).
//
// The Keeper wraps an sdk.KVStore via a storeKey. It holds the ExitRoute
// records (by route-id) and the DEXSwap records (by swap-id). The Keeper
// also holds the expected-keeper shim (BridgeKeeper for cross-chain exits).
// The shim is an interface (G-003 — no struct import of x/bridge/types);
// the concrete x/bridge keeper satisfies it structurally.
//
// The Fee Covenant clamp (x/feecovenant/types.Clamp) is invoked on
// exit-fee-bps at runtime per the v0.5 interface extension. The clamp
// ensures the exit fee is within [FeeFloorBps=1, FeeCeilingBps=10] (§18
// Mission-Lock Fee Covenant — auto-decline-only, never auto-increase).
//
// State-machine ordering (vision §7, enforced in every handler):
//   ValidateBasic → keeper authz → state mutation → ctx.EventManager().EmitEvent

// Keeper is the store-backed exit keeper.
type Keeper struct {
	cdc          codec.Codec
	storeKey     storetypes.StoreKey
	bridgeKeeper types.BridgeKeeper
}

// NewKeeper constructs a new store-backed exit Keeper. The BridgeKeeper
// expected-keeper shim is injected (nil-able for partial tests; the
// ExecuteDEXSwap handler guards a nil shim for same-chain exits).
func NewKeeper(cdc codec.Codec, storeKey storetypes.StoreKey, bk types.BridgeKeeper) Keeper {
	return Keeper{
		cdc:          cdc,
		storeKey:     storeKey,
		bridgeKeeper: bk,
	}
}

// SetBridgeKeeper sets the BridgeKeeper expected-keeper shim (for
// post-construction wiring, e.g., app wiring or test setup).
func (k *Keeper) SetBridgeKeeper(bk types.BridgeKeeper) { k.bridgeKeeper = bk }

// --- ExitRoute store ----------------------------------------------------------

var routeKeyPrefix = []byte("route/")

func routeKey(routeID string) []byte {
	return append(routeKeyPrefix, []byte(routeID)...)
}

// GetExitRoute loads an ExitRoute by route-id. Returns the route and true
// if found, or zero value + false if not.
func (k Keeper) GetExitRoute(ctx sdk.Context, routeID string) (types.ExitRoute, bool) {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(routeKey(routeID))
	if bz == nil {
		return types.ExitRoute{}, false
	}
	var r types.ExitRoute
	if err := json.Unmarshal(bz, &r); err != nil {
		return types.ExitRoute{}, false
	}
	return r, true
}

// SetExitRoute persists an ExitRoute by route-id.
func (k Keeper) SetExitRoute(ctx sdk.Context, r types.ExitRoute) {
	store := ctx.KVStore(k.storeKey)
	bz, err := json.Marshal(r)
	if err != nil {
		panic(fmt.Sprintf("exit: marshal route %q: %v", r.RouteID, err))
	}
	store.Set(routeKey(r.RouteID), bz)
}

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

// --- DEXSwap store ------------------------------------------------------------

var swapKeyPrefix = []byte("swap/")

func swapKey(swapID string) []byte {
	return append(swapKeyPrefix, []byte(swapID)...)
}

// GetDEXSwap loads a DEXSwap by swap-id. Returns the swap and true if found.
func (k Keeper) GetDEXSwap(ctx sdk.Context, swapID string) (types.DEXSwap, bool) {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(swapKey(swapID))
	if bz == nil {
		return types.DEXSwap{}, false
	}
	var s types.DEXSwap
	if err := json.Unmarshal(bz, &s); err != nil {
		return types.DEXSwap{}, false
	}
	return s, true
}

// SetDEXSwap persists a DEXSwap by swap-id.
func (k Keeper) SetDEXSwap(ctx sdk.Context, s types.DEXSwap) {
	store := ctx.KVStore(k.storeKey)
	bz, err := json.Marshal(s)
	if err != nil {
		panic(fmt.Sprintf("exit: marshal swap %q: %v", s.SwapID, err))
	}
	store.Set(swapKey(s.SwapID), bz)
}

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