package httpapi

import (
	"context"
	"net/http"
	"strings"

	"evobgp/internal/authkey"

	"github.com/golang-jwt/jwt/v5"
)

type ctxKey int

const authCtxKey ctxKey = 1

// Auth kinds distinguish API key sessions from portal JWT sessions.
const (
	AuthKindAPIKey = "apikey"
	AuthKindJWT    = "jwt"
)

// Auth holds resolved API identity for a request.
type Auth struct {
	TenantID string
	Role     string // viewer, editor, operator, node, firewall (apikeys only)
	Token    string
	APIKeyID string // non-empty for DB-managed keys
	// Portal / dual-auth fields (empty for API keys unless noted).
	Kind        string   // "apikey" | "jwt"
	UserID      string   // JWT sub
	Email       string   // JWT email claim
	Permissions []string // JWT permissions claim (bgp:*)
	IsAdmin     bool     // JWT is_admin claim
}

func authFromContext(ctx context.Context) (Auth, bool) {
	a, ok := ctx.Value(authCtxKey).(Auth)
	return a, ok
}

type apiKeyRecord struct {
	token    string
	tenantID string
	role     string
	keyID    string // set for DB-managed keys (last_used_at)
}

func parseAPIKeysSpec(spec string) []apiKeyRecord {
	spec = strings.TrimSpace(spec)
	if spec == "" {
		return nil
	}
	var out []apiKeyRecord
	for _, part := range strings.Split(spec, ",") {
		part = strings.TrimSpace(part)
		if part == "" {
			continue
		}
		fields := strings.Split(part, "|")
		if len(fields) != 3 {
			continue
		}
		out = append(out, apiKeyRecord{
			token:    strings.TrimSpace(fields[0]),
			tenantID: strings.TrimSpace(fields[1]),
			role:     strings.TrimSpace(fields[2]),
		})
	}
	return out
}

// looksLikeJWT reports whether raw is a compact JWS (three dot-separated segments, non-empty).
func looksLikeJWT(raw string) bool {
	if raw == "" {
		return false
	}
	parts := strings.Split(raw, ".")
	if len(parts) != 3 {
		return false
	}
	for _, p := range parts {
		if strings.TrimSpace(p) == "" {
			return false
		}
	}
	return true
}

func (s *Server) authMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		h := r.Header.Get("Authorization")
		const p = "Bearer "
		if !strings.HasPrefix(h, p) {
			writeProblem(w, http.StatusUnauthorized, "Unauthorized", "missing or invalid bearer token")
			return
		}
		raw := strings.TrimSpace(strings.TrimPrefix(h, p))
		if looksLikeJWT(raw) && strings.TrimSpace(s.jwtSecret) != "" {
			a, status, msg, ok := s.resolveJWT(raw)
			if !ok {
				writeProblem(w, status, http.StatusText(status), msg)
				return
			}
			r = r.WithContext(context.WithValue(r.Context(), authCtxKey, a))
			next.ServeHTTP(w, r)
			return
		}
		a, ok := s.resolveAuth(raw)
		if !ok {
			writeProblem(w, http.StatusUnauthorized, "Unauthorized", "unknown api key")
			return
		}
		if a.APIKeyID != "" {
			go func(id string) { _ = s.store.TouchAPIKeyLastUsed(id) }(a.APIKeyID)
		}
		r = r.WithContext(context.WithValue(r.Context(), authCtxKey, a))
		next.ServeHTTP(w, r)
	})
}

func authFromKeyRecord(raw string, rec apiKeyRecord) Auth {
	return Auth{
		Kind:     AuthKindAPIKey,
		TenantID: rec.tenantID,
		Role:     rec.role,
		Token:    raw,
		APIKeyID: rec.keyID,
	}
}

// resolveAuth maps a bearer token to tenant identity (API key path).
// For the literal token "dev", the demo shortcut (devAuth) takes precedence when demo-seed
// is available; env/DB mapping is used only when demo tenant is absent.
func (s *Server) resolveAuth(raw string) (Auth, bool) {
	if raw == "dev" {
		if a, ok := s.devAuth(); ok {
			return a, true
		}
		if rec, ok := s.keyResolver.Lookup(raw); ok {
			return authFromKeyRecord(raw, rec), true
		}
		return Auth{}, false
	}
	rec, ok := s.keyResolver.Lookup(raw)
	if !ok {
		if s.firewallResolver != nil {
			if fw, ok := s.firewallResolver.Lookup(raw); ok {
				return Auth{Kind: AuthKindAPIKey, TenantID: fw.tenantID, Role: "firewall", Token: raw, APIKeyID: fw.clientID}, true
			}
		}
		if client, err := s.store.LookupFirewallClientByTokenHash(authkey.HashToken(raw)); err == nil {
			return Auth{Kind: AuthKindAPIKey, TenantID: client.TenantID, Role: "firewall", Token: raw, APIKeyID: client.ID}, true
		}
		return Auth{}, false
	}
	return authFromKeyRecord(raw, rec), true
}

// resolveJWT parses and validates a portal HS256 token, returning an Auth on success.
// Returns (auth, status, detail, ok). status/detail are used when ok=false.
func (s *Server) resolveJWT(raw string) (Auth, int, string, bool) {
	if strings.TrimSpace(s.portalTenantID) == "" {
		return Auth{}, http.StatusServiceUnavailable, "portal tenant not configured (EVOBGP_PORTAL_TENANT_ID)", false
	}
	tok, err := jwt.Parse(raw, func(t *jwt.Token) (any, error) {
		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, jwt.ErrSignatureInvalid
		}
		return []byte(s.jwtSecret), nil
	}, jwt.WithValidMethods([]string{jwt.SigningMethodHS256.Alg()}))
	if err != nil || tok == nil || !tok.Valid {
		return Auth{}, http.StatusUnauthorized, "invalid jwt", false
	}
	claims, ok := tok.Claims.(jwt.MapClaims)
	if !ok {
		return Auth{}, http.StatusUnauthorized, "invalid jwt claims", false
	}
	if iss := strings.TrimSpace(s.authIssuer); iss != "" {
		got, _ := claims["iss"].(string)
		if strings.TrimSpace(got) != iss {
			return Auth{}, http.StatusUnauthorized, "jwt issuer mismatch", false
		}
	}
	apps := coerceStringSlice(claims["apps"])
	if !containsFold(apps, "bgp") {
		return Auth{}, http.StatusForbidden, "jwt does not grant access to bgp app", false
	}
	sub, _ := claims["sub"].(string)
	if strings.TrimSpace(sub) == "" {
		return Auth{}, http.StatusUnauthorized, "jwt missing sub", false
	}
	email, _ := claims["email"].(string)
	perms := coerceStringSlice(claims["permissions"])
	isAdmin, _ := claims["is_admin"].(bool)
	return Auth{
		Kind:        AuthKindJWT,
		TenantID:    s.portalTenantID,
		UserID:      strings.TrimSpace(sub),
		Email:       strings.TrimSpace(email),
		Permissions: perms,
		IsAdmin:     isAdmin,
		Token:       raw,
	}, 0, "", true
}

func coerceStringSlice(v any) []string {
	switch t := v.(type) {
	case []string:
		return t
	case []any:
		out := make([]string, 0, len(t))
		for _, x := range t {
			if s, ok := x.(string); ok {
				out = append(out, s)
			}
		}
		return out
	default:
		return nil
	}
}

func containsFold(items []string, needle string) bool {
	for _, x := range items {
		if strings.EqualFold(strings.TrimSpace(x), needle) {
			return true
		}
	}
	return false
}

func (s *Server) devAuth() (Auth, bool) {
	tid, _, _, _, _ := s.store.DemoIDs()
	if tid == "" {
		return Auth{}, false
	}
	return Auth{Kind: AuthKindAPIKey, TenantID: tid, Role: "operator", Token: "dev"}, true
}

func roleLevel(role string) int {
	switch strings.ToLower(role) {
	case "viewer":
		return 1
	case "editor":
		return 2
	case "operator":
		return 3
	default:
		return 0
	}
}

// requireAtLeast rejects node/firewall roles and enforces viewer/editor/operator ladder for API keys.
// New code should call requirePerm which supports JWT permissions in addition to API-key roles.
func (s *Server) requireAtLeast(w http.ResponseWriter, a Auth, need string) bool {
	if strings.ToLower(a.Role) == "node" {
		writeProblem(w, http.StatusForbidden, "Forbidden", "node role cannot access this resource")
		return false
	}
	if roleLevel(a.Role) < roleLevel(need) {
		writeProblem(w, http.StatusForbidden, "Forbidden", "insufficient role")
		return false
	}
	return true
}

func (s *Server) requireFirewall(w http.ResponseWriter, a Auth) bool {
	if strings.ToLower(a.Role) != "firewall" {
		writeProblem(w, http.StatusForbidden, "Forbidden", "firewall client role required")
		return false
	}
	return true
}

func (s *Server) requireNode(w http.ResponseWriter, a Auth) bool {
	if strings.ToLower(a.Role) != "node" {
		writeProblem(w, http.StatusForbidden, "Forbidden", "node role required")
		return false
	}
	return true
}