package provisioning

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"strings"

	"git.coopcloud.tech/wiki-cafe/member-console/internal/billing"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/entitlements"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/identity"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/organization"
)

// OIDCClaims holds the claims extracted from OIDC authentication.
type OIDCClaims struct {
	Subject           string
	Email             string
	EmailVerified     bool
	Name              string
	PreferredUsername string
}

// Result holds all records created during auto-provisioning.
type Result struct {
	User           identity.User
	Person         identity.Person
	Org            organization.Organization
	OrgMember      organization.OrgMember
	Workspace      organization.Workspace
	Pool           entitlements.ResourcePool
	PoolAssignment entitlements.PoolAssignment
	BillingAccount billing.Account
	// DefaultGrant is populated only when the org type has a default product configured.
	DefaultGrant *entitlements.ConferGrantResult
}

// AutoProvision creates all governance structures for a new user within a
// single database transaction: user → person → org → org_member → workspace.
func AutoProvision(ctx context.Context, db *sql.DB, claims OIDCClaims) (*Result, error) {
	tx, err := db.BeginTx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("begin transaction: %w", err)
	}
	defer tx.Rollback()

	idQ := identity.New(tx)
	orgQ := organization.New(tx)

	// 1. Create user
	user, err := idQ.CreateUser(ctx, claims.Subject)
	if err != nil {
		return nil, fmt.Errorf("create user: %w", err)
	}

	// 2. Create person
	displayName := DisplayNameFromClaims(claims.Name, claims.PreferredUsername)
	person, err := idQ.CreatePerson(ctx, identity.CreatePersonParams{
		UserID:               user.UserID,
		DisplayName:          displayName,
		PrimaryEmail:         claims.Email,
		PrimaryEmailVerified: claims.EmailVerified,
	})
	if err != nil {
		return nil, fmt.Errorf("create person: %w", err)
	}

	// 3. Create personal organization
	// The name is derived from the display name; nothing is derived from the
	// username. Names are not unique, so there is no collision handling here.
	// The organization gets no key: a key is never derived from a person's
	// login or display name (entity-keys §4), and nothing outside the
	// database addresses a personal organization literally -- it is reached
	// through its owner, whose own key is the OIDC subject her IdP issues.
	orgName := personalOrgName(displayName)

	org, err := orgQ.CreateOrganization(ctx, organization.CreateOrganizationParams{
		Name:          orgName,
		OrgType:       "personal",
		OwnerPersonID: person.PersonID,
	})
	if err != nil {
		return nil, fmt.Errorf("create organization: %w", err)
	}

	// 4. Look up the owner system role
	ownerRole, err := orgQ.GetSystemRoleByName(ctx, "owner")
	if err != nil {
		return nil, fmt.Errorf("get owner role: %w", err)
	}

	// 5. Create org membership
	orgMember, err := orgQ.CreateOrgMember(ctx, organization.CreateOrgMemberParams{
		OrgID:    org.OrgID,
		PersonID: person.PersonID,
		RoleID:   ownerRole.RoleID,
	})
	if err != nil {
		return nil, fmt.Errorf("create org member: %w", err)
	}

	// 6. Create org-scoped role assignment for the owner
	_, err = orgQ.CreateRoleAssignment(ctx, organization.CreateRoleAssignmentParams{
		RoleID:    ownerRole.RoleID,
		PersonID:  person.PersonID,
		OrgID:     org.OrgID,
		ScopeType: "organization",
		ScopeID:   org.OrgID,
	})
	if err != nil {
		return nil, fmt.Errorf("create role assignment: %w", err)
	}

	// 7. Create the default workspace and its primary assignment to the
	// org's default resource pool (created here, since a brand-new org has
	// none yet) in one shared step -- the same one the member "create
	// workspace" handler uses, so this rule has exactly one implementation
	// (schema-hardening design D2).
	wsResult, err := CreateWorkspaceWithPrimaryAssignment(ctx, tx, org.OrgID, "Default")
	if err != nil {
		return nil, fmt.Errorf("create workspace: %w", err)
	}
	workspace := wsResult.Workspace
	pool := wsResult.Pool
	poolAssignment := wsResult.PoolAssignment

	// 8. Create default billing account for the organization
	billQ := billing.New(tx)
	billingAccount, err := billQ.CreateBillingAccount(ctx, billing.CreateBillingAccountParams{
		OrgID:    org.OrgID,
		Name:     "Default",
		Status:   "active",
		Metadata: json.RawMessage("{}"),
	})
	if err != nil {
		return nil, fmt.Errorf("create billing account: %w", err)
	}

	// 9. Check org type for default plan ladder policy
	var defaultGrant *entitlements.ConferGrantResult
	orgTypeConfig, err := orgQ.GetOrgType(ctx, "personal")
	if err != nil {
		return nil, fmt.Errorf("get org type config: %w", err)
	}

	if orgTypeConfig.DefaultPlanLadderID.Valid {
		// 10. Resolve the rank-0 tier of the configured ladder to get the
		// default product, then confer the grant so the pool starts on the
		// correct tier. Conferral writes the position and transition rows.
		//
		// A missing rank-0 tier (out-of-band damage: e.g. the ladder's last
		// tier was deleted outside the app-level guard) must not fail the
		// signup with a 500 -- every other governance structure above is
		// already valid and worth keeping. Skip conferral, complete
		// provisioning plan-less, and log loudly: the org is repairable
		// later via ReapplyDefaultsIfVacant once the ladder is fixed
		// (schema-hardening design D4b).
		ladderID := orgTypeConfig.DefaultPlanLadderID.UUID.String()
		bq := billing.New(tx)
		rankZero, err := bq.GetTierByLadderRank(ctx, billing.GetTierByLadderRankParams{
			PlanLadderID: ladderID,
			Rank:         0,
		})
		switch {
		case err == nil:
			// GrantedByPersonID stays "" (system-authored) as required for grant_reason "default".
			defaultGrant, err = entitlements.ConferGrantTx(ctx, tx, entitlements.ConferGrantInput{
				ProductID:        rankZero.ProductID,
				OrgID:            org.OrgID,
				GrantReason:      "default",
				Quantity:         1,
				ActorType:        "system",
				TransitionReason: "auto-provisioning on org creation",
			})
			if err != nil {
				return nil, fmt.Errorf("confer default grant: %w", err)
			}
		case errors.Is(err, sql.ErrNoRows):
			slog.Default().Error(
				"AUTO-PROVISIONING ALARM: default plan ladder has no rank-0 tier -- signup completed WITHOUT a plan",
				slog.String("org_type", orgTypeConfig.OrgType),
				slog.String("plan_ladder_id", ladderID),
				slog.String("org_id", org.OrgID),
				slog.String("user_id", user.UserID),
			)
		default:
			return nil, fmt.Errorf("resolve rank-0 tier of default ladder %s: %w", ladderID, err)
		}
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("commit transaction: %w", err)
	}

	return &Result{
		User:           user,
		Person:         person,
		Org:            org,
		OrgMember:      orgMember,
		Workspace:      workspace,
		Pool:           pool,
		PoolAssignment: poolAssignment,
		BillingAccount: billingAccount,
		DefaultGrant:   defaultGrant,
	}, nil
}

// personalOrgName derives a personal organization name from a display name.
// e.g., "Carlos" → "Carlos's Organization"
func personalOrgName(displayName string) string {
	if displayName == "" {
		return "Personal Organization"
	}
	if strings.HasSuffix(displayName, "s") || strings.HasSuffix(displayName, "S") {
		return displayName + "' Organization"
	}
	return displayName + "'s Organization"
}

// DisplayNameFromClaims picks the display name an IdP's claims support: the
// `name` claim, else `preferred_username`, else "" (callers keep whatever
// they already hold when both are empty). First-login provisioning and the
// returning-login resync in internal/auth use the same rule, so a login can
// never downgrade a display name to an empty string.
func DisplayNameFromClaims(name, preferredUsername string) string {
	if n := strings.TrimSpace(name); n != "" {
		return n
	}
	return strings.TrimSpace(preferredUsername)
}