package openapi

import (
	"context"
	"errors"
	"time"

	"github.com/danielgtaylor/huma/v2"

	"anchorage/internal/pkg/auth"
	"anchorage/internal/pkg/cache"
	"anchorage/internal/pkg/ids"
	"anchorage/internal/pkg/maintenance"
	"anchorage/internal/pkg/node"
	"anchorage/internal/pkg/scheduler"
	"anchorage/internal/pkg/store"
)

type auditBody struct {
	ID          int64          `json:"id"`
	Action      string         `json:"action"`
	Target      string         `json:"target"`
	Result      string         `json:"result"`
	Detail      map[string]any `json:"detail,omitempty"`
	ActorUserID string         `json:"actor_user_id,omitempty"`
	OrgID       string         `json:"org_id,omitempty"`
	Created     time.Time      `json:"created"`
}

func ifUserID(p *ids.UserID) string {
	if p == nil {
		return ""
	}
	return p.String()
}
func ifOrgID(p *ids.OrgID) string {
	if p == nil {
		return ""
	}
	return p.String()
}

// AdminDeps holds the collaborators the admin endpoints need.
type AdminDeps struct {
	Store      store.Store
	Maint      *maintenance.Manager
	Rebalancer *scheduler.Rebalancer
	// Presences is the source of real-time NATS heartbeat data
	// (distinct from the DB view via Store.Nodes().ListAll()). Used by
	// /v1/admin/cluster/presences to let operators compare what each
	// node is broadcasting right now against the DB registry.
	Presences PresenceSource
}

// PresenceSource is implemented by *node.Runner. Narrow interface so
// tests can stub; the real implementation returns a snapshot of the
// in-memory heartbeat map keyed by NodeID.
type PresenceSource interface {
	LivePresences() []node.Presence
}

// NodePresence is the admin-API projection of node.Presence. Kept in
// openapi so the HTTP response shape stays stable even if the internal
// node.Presence struct evolves.
type NodePresence struct {
	NodeID     string    `json:"node_id"`
	Multiaddrs []string  `json:"multiaddrs"`
	Status     string    `json:"status"`
	SentAt     time.Time `json:"sent_at"`
	// AgeSeconds is derived server-side so clients don't have to
	// reason about clock skew — operators eyeballing the response can
	// see "last heard 12s ago" directly.
	AgeSeconds float64 `json:"age_seconds"`
}

// RegisterAdmin wires drain/uncordon/maintenance endpoints at
// /v1/admin/*. Access is restricted to sysadmins; orgadmins cannot
// drain nodes (that would be a cluster-level action).
func RegisterAdmin(api huma.API, deps AdminDeps) {
	huma.Register(api, huma.Operation{
		OperationID: "adminDrain",
		Method:      "POST",
		Path:        "/admin/nodes/{node_id}/drain",
		Summary:     "Drain a cluster node",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, in *struct {
		NodeID string `path:"node_id"`
	}) (*struct {
		Body struct {
			OK bool `json:"ok"`
		}
	}, error) {
		if err := requireSysadmin(ctx); err != nil {
			return nil, err
		}
		nid, err := ids.ParseNode(in.NodeID)
		if err != nil {
			return nil, huma.Error400BadRequest("bad node id")
		}
		if err := deps.Store.Nodes().Drain(ctx, nid); err != nil {
			return nil, huma.Error500InternalServerError("drain", err)
		}
		out := &struct {
			Body struct {
				OK bool `json:"ok"`
			}
		}{}
		out.Body.OK = true
		return out, nil
	})

	huma.Register(api, huma.Operation{
		OperationID: "adminUncordon",
		Method:      "POST",
		Path:        "/admin/nodes/{node_id}/uncordon",
		Summary:     "Return a drained node to service",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, in *struct {
		NodeID string `path:"node_id"`
	}) (*struct {
		Body struct {
			OK bool `json:"ok"`
		}
	}, error) {
		if err := requireSysadmin(ctx); err != nil {
			return nil, err
		}
		nid, err := ids.ParseNode(in.NodeID)
		if err != nil {
			return nil, huma.Error400BadRequest("bad node id")
		}
		if err := deps.Store.Nodes().Uncordon(ctx, nid); err != nil {
			return nil, huma.Error500InternalServerError("uncordon", err)
		}
		out := &struct {
			Body struct {
				OK bool `json:"ok"`
			}
		}{}
		out.Body.OK = true
		return out, nil
	})

	type maintenanceStatusBody struct {
		On        bool      `json:"on"`
		Reason    string    `json:"reason,omitempty"`
		SetBy     string    `json:"set_by,omitempty"`
		SetAt     time.Time `json:"set_at,omitempty"`
		ExpiresAt time.Time `json:"expires_at,omitempty"`
	}

	huma.Register(api, huma.Operation{
		OperationID: "adminMaintenanceOn",
		Method:      "POST",
		Path:        "/admin/maintenance/on",
		Summary:     "Enable cluster-wide maintenance",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, in *struct {
		Body struct {
			Reason string        `json:"reason,omitempty"`
			TTL    time.Duration `json:"ttl,omitempty"`
		}
	}) (*struct {
		Body maintenanceStatusBody
	}, error) {
		cc, err := requireSysadminCC(ctx)
		if err != nil {
			return nil, err
		}
		f := maintenance.Flag{
			Reason: in.Body.Reason,
			SetBy:  cc.User.String(),
			SetAt:  time.Now().UTC(),
		}
		if in.Body.TTL > 0 {
			f.ExpiresAt = f.SetAt.Add(in.Body.TTL)
		}
		if err := deps.Maint.Set(ctx, f); err != nil {
			return nil, huma.Error500InternalServerError("maintenance on", err)
		}
		out := &struct{ Body maintenanceStatusBody }{}
		out.Body = maintenanceStatusBody{
			On: true, Reason: f.Reason, SetBy: f.SetBy, SetAt: f.SetAt, ExpiresAt: f.ExpiresAt,
		}
		return out, nil
	})

	huma.Register(api, huma.Operation{
		OperationID: "adminMaintenanceOff",
		Method:      "POST",
		Path:        "/admin/maintenance/off",
		Summary:     "Disable cluster-wide maintenance",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, _ *struct{}) (*struct {
		Body maintenanceStatusBody
	}, error) {
		if err := requireSysadmin(ctx); err != nil {
			return nil, err
		}
		if err := deps.Maint.Clear(ctx); err != nil {
			return nil, huma.Error500InternalServerError("maintenance off", err)
		}
		out := &struct{ Body maintenanceStatusBody }{}
		return out, nil
	})

	huma.Register(api, huma.Operation{
		OperationID: "adminGrantSysadmin",
		Method:      "POST",
		Path:        "/admin/users/{email}/grant-sysadmin",
		Summary:     "Promote an existing user to sysadmin",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, in *struct {
		Email string `path:"email"`
	}) (*struct {
		Body struct {
			OK bool `json:"ok"`
		}
	}, error) {
		cc, err := requireSysadminCC(ctx)
		if err != nil {
			return nil, err
		}
		user, err := deps.Store.Users().GetByEmail(ctx, in.Email)
		if err != nil {
			if errors.Is(err, store.ErrNotFound) {
				return nil, huma.Error404NotFound("user (must have logged in at least once via Authentik)")
			}
			return nil, huma.Error500InternalServerError("lookup", err)
		}
		if err := deps.Store.Users().PromoteSysadmin(ctx, user.ID); err != nil {
			return nil, huma.Error500InternalServerError("promote", err)
		}
		_ = deps.Store.Audit().Insert(ctx, &store.AuditEntry{
			ActorUserID: &cc.User,
			Action:      "admin.grant-sysadmin",
			Target:      user.ID.String(),
			Result:      "ok",
			Detail:      map[string]any{"email": in.Email},
		})
		out := &struct {
			Body struct {
				OK bool `json:"ok"`
			}
		}{}
		out.Body.OK = true
		return out, nil
	})

	huma.Register(api, huma.Operation{
		OperationID: "adminListAudit",
		Method:      "GET",
		Path:        "/admin/audit",
		Summary:     "Paged audit-log listing",
		Description: "sysadmin with no org_id sees every org; org members can only read their own org's audit",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, in *struct {
		OrgID  string `query:"org_id"`
		Limit  int    `query:"limit"  default:"50" minimum:"1" maximum:"1000"`
		Offset int    `query:"offset" default:"0"  minimum:"0"`
	}) (*struct {
		Body struct {
			Results []auditBody `json:"results"`
		}
	}, error) {
		cc, err := auth.Require(ctx)
		if err != nil {
			return nil, huma.Error401Unauthorized("auth")
		}
		var scopeOrg ids.OrgID
		if in.OrgID != "" {
			scopeOrg, err = ids.ParseOrg(in.OrgID)
			if err != nil {
				return nil, huma.Error400BadRequest("bad org id")
			}
			if cc.Role != "sysadmin" && scopeOrg != cc.Org {
				return nil, huma.Error403Forbidden("cannot view other org's audit")
			}
		} else if cc.Role != "sysadmin" {
			scopeOrg = cc.Org
		}
		rows, err := deps.Store.Audit().List(ctx, scopeOrg, in.Limit, in.Offset)
		if err != nil {
			return nil, huma.Error500InternalServerError("list", err)
		}
		out := &struct {
			Body struct {
				Results []auditBody `json:"results"`
			}
		}{}
		for _, e := range rows {
			out.Body.Results = append(out.Body.Results, auditBody{
				ID:          e.ID,
				Action:      e.Action,
				Target:      e.Target,
				Result:      e.Result,
				Detail:      e.Detail,
				ActorUserID: ifUserID(e.ActorUserID),
				OrgID:       ifOrgID(e.OrgID),
				Created:     e.Created,
			})
		}
		return out, nil
	})

	huma.Register(api, huma.Operation{
		OperationID: "adminMaintenanceStatus",
		Method:      "GET",
		Path:        "/admin/maintenance",
		Summary:     "Report current cluster-maintenance state",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, _ *struct{}) (*struct {
		Body maintenanceStatusBody
	}, error) {
		if err := requireSysadmin(ctx); err != nil {
			return nil, err
		}
		f, on, err := deps.Maint.IsOn(ctx)
		if err != nil {
			return nil, huma.Error500InternalServerError("maintenance status", err)
		}
		out := &struct{ Body maintenanceStatusBody }{}
		if on && f != nil {
			out.Body = maintenanceStatusBody{
				On: true, Reason: f.Reason, SetBy: f.SetBy,
				SetAt: f.SetAt, ExpiresAt: f.ExpiresAt,
			}
		}
		return out, nil
	})

	// ---- prune-denylist ----------------------------------------------------
	huma.Register(api, huma.Operation{
		OperationID: "adminPruneTokenDenylist",
		Method:      "POST",
		Path:        "/admin/tokens/prune-denylist",
		Summary:     "Delete denylist rows whose expires_at has passed",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, _ *struct{}) (*struct {
		Body struct {
			OK bool `json:"ok"`
		}
	}, error) {
		cc, err := requireSysadminCC(ctx)
		if err != nil {
			return nil, err
		}
		if err := deps.Store.Tokens().PruneDenylist(ctx); err != nil {
			return nil, huma.Error500InternalServerError("prune", err)
		}
		_ = deps.Store.Audit().Insert(ctx, &store.AuditEntry{
			ActorUserID: &cc.User,
			Action:      "admin.prune-denylist",
			Target:      "token_denylist",
			Result:      "ok",
		})
		out := &struct {
			Body struct {
				OK bool `json:"ok"`
			}
		}{}
		out.Body.OK = true
		return out, nil
	})

	// ---- rebalance ---------------------------------------------------------
	type rebalanceReq struct {
		Apply bool `json:"apply,omitempty" doc:"when true, execute the moves; otherwise return a dry-run preview"`
	}
	type rebalanceResp struct {
		Body struct {
			Applied bool                    `json:"applied"`
			Moves   []scheduler.PlannedMove `json:"moves"`
		}
	}
	huma.Register(api, huma.Operation{
		OperationID: "adminRebalance",
		Method:      "POST",
		Path:        "/admin/rebalance",
		Summary:     "One-shot rebalance preview or apply (leader-loop keeps running regardless)",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, in *struct {
		Body rebalanceReq
	}) (*rebalanceResp, error) {
		cc, err := requireSysadminCC(ctx)
		if err != nil {
			return nil, err
		}
		if deps.Rebalancer == nil {
			return nil, huma.Error503ServiceUnavailable("rebalancer not available")
		}
		var moves []scheduler.PlannedMove
		if in.Body.Apply {
			moves, err = deps.Rebalancer.RunOnce(ctx)
		} else {
			moves, err = deps.Rebalancer.DryRun(ctx)
		}
		if err != nil {
			return nil, huma.Error500InternalServerError("rebalance", err)
		}
		if in.Body.Apply {
			_ = deps.Store.Audit().Insert(ctx, &store.AuditEntry{
				ActorUserID: &cc.User,
				Action:      "admin.rebalance",
				Target:      "cluster",
				Result:      "ok",
				Detail:      map[string]any{"moves": len(moves)},
			})
		}
		out := &rebalanceResp{}
		out.Body.Applied = in.Body.Apply
		out.Body.Moves = moves
		return out, nil
	})

	// ---- cache-stats -------------------------------------------------------
	huma.Register(api, huma.Operation{
		OperationID: "adminCacheStats",
		Method:      "GET",
		Path:        "/admin/cache-stats",
		Summary:     "In-memory cache hit/miss/eviction counters per named cache",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, _ *struct{}) (*struct {
		Body struct {
			Caches []cache.Stats `json:"caches"`
		}
	}, error) {
		if err := requireSysadmin(ctx); err != nil {
			return nil, err
		}
		out := &struct {
			Body struct {
				Caches []cache.Stats `json:"caches"`
			}
		}{}
		out.Body.Caches = cache.AllStats()
		return out, nil
	})

	// ---- cluster presences -------------------------------------------------
	//
	// Real-time heartbeat view, distinct from the DB registry. The DB
	// updates status via the stale-sweeper (leader-gated, fires every
	// downAfter interval); this endpoint shows what each peer is
	// broadcasting RIGHT NOW over NATS. Operators comparing the two
	// diagnose "the DB says X is up but nobody's heard from it" gaps.
	huma.Register(api, huma.Operation{
		OperationID: "adminClusterPresences",
		Method:      "GET",
		Path:        "/admin/cluster/presences",
		Summary:     "Real-time NATS heartbeat view of every peer this node has heard from",
		Security:    []map[string][]string{{"accessToken": {}}},
	}, func(ctx context.Context, _ *struct{}) (*struct {
		Body struct {
			Presences []NodePresence `json:"presences"`
		}
	}, error) {
		if err := requireSysadmin(ctx); err != nil {
			return nil, err
		}
		if deps.Presences == nil {
			return nil, huma.Error503ServiceUnavailable("presence source not wired")
		}
		now := time.Now()
		raw := deps.Presences.LivePresences()
		out := &struct {
			Body struct {
				Presences []NodePresence `json:"presences"`
			}
		}{}
		out.Body.Presences = make([]NodePresence, 0, len(raw))
		for _, p := range raw {
			out.Body.Presences = append(out.Body.Presences, NodePresence{
				NodeID:     p.NodeID,
				Multiaddrs: p.Multiaddrs,
				Status:     p.Status,
				SentAt:     p.SentAt,
				AgeSeconds: now.Sub(p.SentAt).Seconds(),
			})
		}
		return out, nil
	})
}

// requireSysadmin rejects any request without a sysadmin client context.
func requireSysadmin(ctx context.Context) error {
	_, err := requireSysadminCC(ctx)
	return err
}

func requireSysadminCC(ctx context.Context) (*auth.ClientContext, error) {
	cc, err := auth.Require(ctx)
	if err != nil {
		return nil, huma.Error401Unauthorized("auth")
	}
	if cc.Role != "sysadmin" {
		return nil, huma.Error403Forbidden("sysadmin required")
	}
	return cc, nil
}