package keeper

import (
	"fmt"

	sdk "github.com/cosmos/cosmos-sdk/types"

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

// msg_server.go implements the partner module's Anchor-credential MsgServer
// (P3-02-01, REQ-035; G-023 ownership split: cosmos-engineer scaffolds the
// file structure + method signatures; backend-engineer implements the
// handler logic bodies). The MsgServer wraps the Keeper + the WatcherKeeper
// and HubKeeper expected-keeper shims (already on the Keeper).
//
// Each method returns a (*Response, error). Handler state-machine ordering
// is enforced: ValidateBasic → keeper authz → state mutation →
// ctx.EventManager().EmitEvent.
//
// Lifecycle (REQ-035, vision §13):
//   - IssueAnchorCredential    → Pending  (Watcher 6-of-9 quorum authz)
//   - OnboardAnchor            → Pending → Onboarded  (HubKeeper custody-
//                              provider-id validity check)
//   - SuspendAnchorCredential  → Onboarded → Suspended
//   - RevokeAnchorCredential   → any → Revoked  (Watcher 6-of-9 quorum authz)
//
// Invalid transitions are REJECTED (the simtest covers each). Revoked is
// terminal (idempotent reject on a second Revoke — NOT double-effect).
//
// Nil-shim behavior (simtest wiring): a nil WatcherKeeper shim skips the
// Watcher quorum authz (the handler still mutates state — the simtest
// documents the wiring contract). A nil HubKeeper shim skips the
// custody-service-exists check (the OnboardAnchor still transitions — the
// simtest documents the wiring contract). The P3→P4 hub dep edge: in P3
// simtest, the HubKeeper shim is wired to a stub (G-003 test exemption);
// the real hub keeper is wired in P4.

// msgServer is the concrete MsgServer implementation wrapping the Keeper.
type msgServer struct {
	Keeper
}

// NewMsgServerImpl returns the partner MsgServer for the provided Keeper.
func NewMsgServerImpl(k Keeper) types.MsgServer {
	return &msgServer{Keeper: k}
}

var _ types.MsgServer = msgServer{}

// unwrapCtx extracts the sdk.Context from the interface-typed ctx.
func unwrapCtx(ctx interface{}) sdk.Context {
	if c, ok := ctx.(sdk.Context); ok {
		return c
	}
	panic(fmt.Sprintf("partner: expected sdk.Context, got %T", ctx))
}

// nowUnix returns the current block time as unix seconds from the ctx.
func nowUnix(ctx sdk.Context) int64 {
	return ctx.BlockTime().Unix()
}

// issuePayload is the byte payload the Watcher quorum signs over for an
// IssueAnchorCredential. It binds the anchor-id + credential-uri + issuer
// to the quorum signature (a quorum signature over a different payload
// does not authorize this issuance).
func issuePayload(msg *types.MsgIssueAnchorCredential) []byte {
	return []byte(fmt.Sprintf("partner.issue:%s:%s:%s", msg.AnchorID, msg.CredentialURI, msg.Issuer))
}

// revokePayload is the byte payload the Watcher quorum signs over for a
// RevokeAnchorCredential. It binds the anchor-id + signer to the quorum
// signature (a quorum signature over a different payload does not
// authorize this revocation).
func revokePayload(msg *types.MsgRevokeAnchorCredential) []byte {
	return []byte(fmt.Sprintf("partner.revoke:%s:%s", msg.AnchorID, msg.Signer))
}

// --- IssueAnchorCredential (creates credential status=Pending) ---------------

// IssueAnchorCredential issues an Anchor credential (status=Pending).
// The handler enforces:
//  1. ValidateBasic (stateless).
//  2. Idempotency: anchor-id must not already exist.
//  3. Watcher 6-of-9 quorum authz (REQ-004) via the WatcherKeeper shim
//     on the issuance payload. A nil shim skips this check (simtest
//     wiring); a non-nil shim that returns false REJECTS the issuance.
//
// On success the credential is persisted with status=Pending and an
// event is emitted.
func (s msgServer) IssueAnchorCredential(ctx interface{}, msg *types.MsgIssueAnchorCredential) (*types.MsgIssueAnchorCredentialResponse, error) {
	if err := msg.ValidateBasic(); err != nil {
		return nil, err
	}
	sdkCtx := unwrapCtx(ctx)

	// Idempotency: anchor-id must not already exist.
	if _, ok := s.Keeper.GetAnchorCredential(sdkCtx, msg.AnchorID); ok {
		return nil, fmt.Errorf("partner: anchor credential %q already exists", msg.AnchorID)
	}

	// Watcher 6-of-9 quorum authz (REQ-004). A nil shim skips the authz
	// (simtest wiring); a non-nil shim that returns false REJECTS.
	if s.Keeper.watcherKeeper != nil {
		if !s.Keeper.watcherKeeper.IsQuorumSigned(msg.WatcherQuorumID, issuePayload(msg)) {
			return nil, fmt.Errorf("partner: watcher quorum %q did not authorize issuance of anchor %q (REQ-004 6-of-9)", msg.WatcherQuorumID, msg.AnchorID)
		}
	}

	cred := types.AnchorCredential{
		AnchorID:          msg.AnchorID,
		CustodyProviderID: "", // empty — set on OnboardAnchor
		CredentialURI:     msg.CredentialURI,
		AttestationCount:  0,
		Status:            types.AnchorPending,
	}
	s.Keeper.SetAnchorCredential(sdkCtx, cred)

	sdkCtx.EventManager().EmitEvent(sdk.NewEvent(
		"partner.anchor_credential_issued",
		sdk.NewAttribute("anchor_id", msg.AnchorID),
		sdk.NewAttribute("credential_uri", msg.CredentialURI),
		sdk.NewAttribute("watcher_quorum_id", msg.WatcherQuorumID),
		sdk.NewAttribute("issuer", msg.Issuer),
		sdk.NewAttribute("status", string(types.AnchorPending)),
	))
	return &types.MsgIssueAnchorCredentialResponse{}, nil
}

// --- OnboardAnchor (Pending → Onboarded) -------------------------------------

// OnboardAnchor transitions an Anchor credential Pending → Onboarded.
// The handler enforces:
//  1. ValidateBasic (stateless).
//  2. The credential must exist.
//  3. The source status must be Pending (ValidAnchorTransition(Pending,
//     Onboarded) — the lifecycle gate).
//  4. The custody-provider-id must reference a LIVE Hub custody service
//     via the HubKeeper shim (the P3→P4 hub dep edge). A nil shim skips
//     this check (simtest wiring); a non-nil shim that returns false
//     REJECTS the onboarding (the credential stays Pending).
//  5. The custody-provider-id on the credential is set from the msg
//     (the msg carries the custody-provider-id to bind to).
//
// On success the credential's CustodyProviderID is set, the status is
// transitioned to Onboarded, and an event is emitted.
func (s msgServer) OnboardAnchor(ctx interface{}, msg *types.MsgOnboardAnchor) (*types.MsgOnboardAnchorResponse, error) {
	if err := msg.ValidateBasic(); err != nil {
		return nil, err
	}
	sdkCtx := unwrapCtx(ctx)

	cred, ok := s.Keeper.GetAnchorCredential(sdkCtx, msg.AnchorID)
	if !ok {
		return nil, fmt.Errorf("partner: anchor credential %q not found", msg.AnchorID)
	}

	// Lifecycle gate: Pending → Onboarded is the only valid transition
	// into Onboarded.
	if !types.ValidAnchorTransition(cred.Status, types.AnchorOnboarded) {
		return nil, fmt.Errorf("partner: anchor %q status %q cannot transition to Onboarded (REQ-035 lifecycle)", msg.AnchorID, cred.Status)
	}

	// HubKeeper custody-service-exists check (the P3→P4 hub dep edge).
	// A nil shim skips the check (simtest wiring); a non-nil shim that
	// returns false REJECTS the onboarding (the credential stays Pending).
	if s.Keeper.hubKeeper != nil {
		if !s.Keeper.hubKeeper.CustodyServiceExists(msg.CustodyProviderID) {
			return nil, fmt.Errorf("partner: custody service %q does not exist (OnboardAnchor rejected — anchor %q stays Pending)", msg.CustodyProviderID, msg.AnchorID)
		}
	}

	// Transition: set custody-provider-id + status=Onboarded.
	cred.CustodyProviderID = msg.CustodyProviderID
	cred.Status = types.AnchorOnboarded
	s.Keeper.SetAnchorCredential(sdkCtx, cred)

	sdkCtx.EventManager().EmitEvent(sdk.NewEvent(
		"partner.anchor_onboarded",
		sdk.NewAttribute("anchor_id", msg.AnchorID),
		sdk.NewAttribute("custody_provider_id", msg.CustodyProviderID),
		sdk.NewAttribute("status", string(types.AnchorOnboarded)),
	))
	return &types.MsgOnboardAnchorResponse{}, nil
}

// --- SuspendAnchorCredential (Onboarded → Suspended) ------------------------

// SuspendAnchorCredential transitions an Anchor credential
// Onboarded → Suspended. The handler enforces:
//  1. ValidateBasic (stateless).
//  2. The credential must exist.
//  3. The source status must be Onboarded (ValidAnchorTransition(Onboarded,
//     Suspended) — the lifecycle gate).
//
// On success the status is transitioned to Suspended and an event is
// emitted.
func (s msgServer) SuspendAnchorCredential(ctx interface{}, msg *types.MsgSuspendAnchorCredential) (*types.MsgSuspendAnchorCredentialResponse, error) {
	if err := msg.ValidateBasic(); err != nil {
		return nil, err
	}
	sdkCtx := unwrapCtx(ctx)

	cred, ok := s.Keeper.GetAnchorCredential(sdkCtx, msg.AnchorID)
	if !ok {
		return nil, fmt.Errorf("partner: anchor credential %q not found", msg.AnchorID)
	}

	if !types.ValidAnchorTransition(cred.Status, types.AnchorSuspended) {
		return nil, fmt.Errorf("partner: anchor %q status %q cannot transition to Suspended (REQ-035 lifecycle)", msg.AnchorID, cred.Status)
	}

	cred.Status = types.AnchorSuspended
	s.Keeper.SetAnchorCredential(sdkCtx, cred)

	sdkCtx.EventManager().EmitEvent(sdk.NewEvent(
		"partner.anchor_credential_suspended",
		sdk.NewAttribute("anchor_id", msg.AnchorID),
		sdk.NewAttribute("status", string(types.AnchorSuspended)),
	))
	return &types.MsgSuspendAnchorCredentialResponse{}, nil
}

// --- RevokeAnchorCredential (any → Revoked, Watcher quorum authz) ------------

// RevokeAnchorCredential transitions an Anchor credential to Revoked
// (terminal). The handler enforces:
//  1. ValidateBasic (stateless).
//  2. The credential must exist.
//  3. The credential must not already be Revoked (idempotent reject — a
//     second Revoke returns an error; NOT double-effect).
//  4. Watcher 6-of-9 quorum authz (REQ-004) via the WatcherKeeper shim
//     on the revocation payload. A nil shim skips this check (simtest
//     wiring); a non-nil shim that returns false REJECTS the revocation.
//
// On success the status is transitioned to Revoked (terminal) and an
// event is emitted.
func (s msgServer) RevokeAnchorCredential(ctx interface{}, msg *types.MsgRevokeAnchorCredential) (*types.MsgRevokeAnchorCredentialResponse, error) {
	if err := msg.ValidateBasic(); err != nil {
		return nil, err
	}
	sdkCtx := unwrapCtx(ctx)

	cred, ok := s.Keeper.GetAnchorCredential(sdkCtx, msg.AnchorID)
	if !ok {
		return nil, fmt.Errorf("partner: anchor credential %q not found", msg.AnchorID)
	}

	// Idempotent reject: a Revoked credential cannot be re-revoked.
	if cred.Status == types.AnchorRevoked {
		return nil, fmt.Errorf("partner: anchor %q already revoked (idempotent reject — no double-effect)", msg.AnchorID)
	}

	// Watcher 6-of-9 quorum authz (REQ-004). A nil shim skips the authz
	// (simtest wiring); a non-nil shim that returns false REJECTS.
	if s.Keeper.watcherKeeper != nil {
		if !s.Keeper.watcherKeeper.IsQuorumSigned(msg.WatcherQuorumID, revokePayload(msg)) {
			return nil, fmt.Errorf("partner: watcher quorum %q did not authorize revocation of anchor %q (REQ-004 6-of-9)", msg.WatcherQuorumID, msg.AnchorID)
		}
	}

	cred.Status = types.AnchorRevoked
	s.Keeper.SetAnchorCredential(sdkCtx, cred)

	sdkCtx.EventManager().EmitEvent(sdk.NewEvent(
		"partner.anchor_credential_revoked",
		sdk.NewAttribute("anchor_id", msg.AnchorID),
		sdk.NewAttribute("watcher_quorum_id", msg.WatcherQuorumID),
		sdk.NewAttribute("status", string(types.AnchorRevoked)),
	))
	return &types.MsgRevokeAnchorCredentialResponse{}, nil
}