// Package queryapi: real handler implementations for the
// SuperAdminSchemaService routes declared in the OpenAPI spec.
//
// Each handler:
//  1. Extracts the authenticated Cognito subject via cognitoauth.GetUserSubject.
//     The handler never trusts a body-supplied "createdBy" — the request schema
//     does not even expose the field, and the service takes the actor as a
//     separate argument.
//  2. Binds the request body (for POST) into the generated request type.
//  3. Delegates to customschema.Service.
//  4. Maps customschema sentinel errors and validator errors onto HTTP codes.
//  5. Serializes the returned model into the generated response type.
package queryapi

import (
	"encoding/json"
	"errors"
	"log/slog"
	"net/http"
	"strings"
	"time"

	"queryorchestration/internal/cognitoauth"
	"queryorchestration/internal/customschema"

	"github.com/google/uuid"
	"github.com/labstack/echo/v4"
	openapi_types "github.com/oapi-codegen/runtime/types"
)

// validatorErrorMarker is the prefix customschema.Service wraps around every
// validator failure it surfaces from CreateSchema / CreateSchemaVersion. The
// handler layer uses it (via strings.Contains) to distinguish a 400-class
// validation problem from a 500-class infrastructure error after sentinel
// checks have already ruled out ErrSchemaNotFound, ErrSchemaInUse, etc.
const validatorErrorMarker = "validate schema definition"

// customSchemaListRow is a type alias onto the anonymous element type that
// oapi-codegen produced inside CustomSchemaListResponse.Schemas. Using an
// alias (not a new type) preserves Go's structural identity so we can append
// directly into the generated slice.
type customSchemaListRow = struct {
	// CanDelete True when documentCount is zero.
	CanDelete bool `json:"canDelete"`

	// ClientId The client that owns this schema.
	ClientId string `json:"clientId"`

	// CreatedAt Timestamp when this schema row was created.
	CreatedAt time.Time `json:"createdAt"`

	// CreatedBy Cognito subject ID (JWT sub claim) of the caller. Opaque UUID, not an email.
	CreatedBy string `json:"createdBy"`

	// Description Optional human-readable description of the schema.
	Description *string `json:"description,omitempty"`

	// DocumentCount Number of documents referencing this schema version.
	DocumentCount int32 `json:"documentCount"`

	// Id The schema row ID.
	Id openapi_types.UUID `json:"id"`

	// Name The schema name (shared across versions in a lineage).
	Name string `json:"name"`

	// Status Lifecycle state of a client_metadata_schemas row. `active` is
	// the version currently assignable to new documents. `superseded`
	// is automatically set when a newer version of the same (clientId,
	// name) lineage is created via POST /versions. `retired` is set
	// when a super_admin explicitly deletes an unused schema.
	Status SchemaStatus `json:"status"`

	// Version Monotonic version number within the lineage.
	Version int32 `json:"version"`
}

// CreateCustomSchema is POST /super-admin/custom-schemas.
//
// Body: CustomSchemaRequest. Actor: JWT subject. Returns 201 with the full
// CustomSchemaResponse on success.
func (s *Controllers) CreateCustomSchema(ctx echo.Context) error {
	actor, ok := cognitoauth.GetUserSubject(ctx)
	if !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "missing user subject")
	}

	var req CustomSchemaRequest
	if err := ctx.Bind(&req); err != nil {
		slog.Error("failed to parse custom schema request", "error", err)
		return echo.NewHTTPError(http.StatusBadRequest, "invalid request body")
	}

	schemaBytes, err := json.Marshal(req.Schema)
	if err != nil {
		return echo.NewHTTPError(http.StatusBadRequest, "invalid schema JSON")
	}

	description := ""
	if req.Description != nil {
		description = *req.Description
	}

	input := customschema.CreateSchemaInput{
		ClientID:    req.ClientId,
		Name:        req.Name,
		Description: description,
		SchemaDef:   schemaBytes,
	}

	created, err := s.svc.CustomSchema.CreateSchema(ctx.Request().Context(), input, actor)
	if err != nil {
		return mapCustomSchemaError(err)
	}

	resp, err := schemaToResponse(created, 0)
	if err != nil {
		return echo.NewHTTPError(http.StatusInternalServerError, "failed to encode schema response")
	}
	return ctx.JSON(http.StatusCreated, resp)
}

// ListCustomSchemas is GET /super-admin/custom-schemas. The required
// clientId query parameter is enforced by the generated wrapper; the
// handler still guards for an empty string to fail fast with a clear 400.
func (s *Controllers) ListCustomSchemas(ctx echo.Context, params ListCustomSchemasParams) error {
	if _, ok := cognitoauth.GetUserSubject(ctx); !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "missing user subject")
	}

	if strings.TrimSpace(params.ClientId) == "" {
		return echo.NewHTTPError(http.StatusBadRequest, "clientId is required")
	}

	filters := customschema.ListFilters{
		Limit:  50,
		Offset: 0,
	}
	if params.Name != nil {
		filters.Name = *params.Name
	}
	if params.IncludeAllVersions != nil {
		filters.IncludeAllVersions = *params.IncludeAllVersions
	}
	if params.Limit != nil {
		if *params.Limit < 1 || *params.Limit > 200 {
			return echo.NewHTTPError(http.StatusBadRequest, "limit must be between 1 and 200")
		}
		filters.Limit = *params.Limit
	}
	if params.Offset != nil {
		if *params.Offset < 0 {
			return echo.NewHTTPError(http.StatusBadRequest, "offset must be >= 0")
		}
		filters.Offset = *params.Offset
	}
	if params.Status != nil {
		if *params.Status == ListCustomSchemasParamsStatusAny {
			filters.StatusAny = true
		} else {
			filters.Status = string(*params.Status)
		}
	}

	summaries, err := s.svc.CustomSchema.ListSchemas(ctx.Request().Context(), params.ClientId, filters)
	if err != nil {
		return mapCustomSchemaError(err)
	}

	resp := CustomSchemaListResponse{
		Schemas: make([]customSchemaListRow, 0, len(summaries)),
	}
	for _, sum := range summaries {
		resp.Schemas = append(resp.Schemas, summaryToListRow(sum))
	}
	return ctx.JSON(http.StatusOK, resp)
}

// GetCustomSchema is GET /super-admin/custom-schemas/{schemaId}.
func (s *Controllers) GetCustomSchema(ctx echo.Context, schemaId openapi_types.UUID) error {
	if _, ok := cognitoauth.GetUserSubject(ctx); !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "missing user subject")
	}

	summary, err := s.svc.CustomSchema.GetSchema(ctx.Request().Context(), uuid.UUID(schemaId))
	if err != nil {
		return mapCustomSchemaError(err)
	}

	resp, err := schemaToResponse(&summary.Schema, summary.DocumentCount)
	if err != nil {
		return echo.NewHTTPError(http.StatusInternalServerError, "failed to encode schema response")
	}
	return ctx.JSON(http.StatusOK, resp)
}

// CreateCustomSchemaVersion is POST /super-admin/custom-schemas/{schemaId}/versions.
func (s *Controllers) CreateCustomSchemaVersion(ctx echo.Context, schemaId openapi_types.UUID) error {
	actor, ok := cognitoauth.GetUserSubject(ctx)
	if !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "missing user subject")
	}

	var req CustomSchemaVersionRequest
	if err := ctx.Bind(&req); err != nil {
		slog.Error("failed to parse custom schema version request", "error", err)
		return echo.NewHTTPError(http.StatusBadRequest, "invalid request body")
	}

	schemaBytes, err := json.Marshal(req.Schema)
	if err != nil {
		return echo.NewHTTPError(http.StatusBadRequest, "invalid schema JSON")
	}

	description := ""
	if req.Description != nil {
		description = *req.Description
	}

	input := customschema.CreateSchemaVersionInput{
		Description: description,
		SchemaDef:   schemaBytes,
	}

	created, err := s.svc.CustomSchema.CreateSchemaVersion(ctx.Request().Context(), uuid.UUID(schemaId), input, actor)
	if err != nil {
		return mapCustomSchemaError(err)
	}

	resp, err := schemaToResponse(created, 0)
	if err != nil {
		return echo.NewHTTPError(http.StatusInternalServerError, "failed to encode schema response")
	}
	return ctx.JSON(http.StatusCreated, resp)
}

// DeleteCustomSchema is DELETE /super-admin/custom-schemas/{schemaId}.
func (s *Controllers) DeleteCustomSchema(ctx echo.Context, schemaId openapi_types.UUID) error {
	actor, ok := cognitoauth.GetUserSubject(ctx)
	if !ok {
		return echo.NewHTTPError(http.StatusUnauthorized, "missing user subject")
	}

	if err := s.svc.CustomSchema.DeleteSchema(ctx.Request().Context(), uuid.UUID(schemaId), actor); err != nil {
		return mapCustomSchemaError(err)
	}
	return ctx.NoContent(http.StatusNoContent)
}

// mapCustomSchemaError translates a customschema.Service error into an
// echo.HTTPError with the correct status code and message. Sentinel checks
// run first; anything that looks like a validator failure maps to 400;
// everything else is a 500.
func mapCustomSchemaError(err error) error {
	switch {
	case errors.Is(err, customschema.ErrSchemaNotFound):
		return echo.NewHTTPError(http.StatusNotFound, "schema not found")
	case errors.Is(err, customschema.ErrSchemaInUse):
		return echo.NewHTTPError(http.StatusConflict, "schema is in use by one or more documents and cannot be deleted")
	case errors.Is(err, customschema.ErrSchemaNameConflict):
		return echo.NewHTTPError(http.StatusConflict, "schema with this duplicate name already exists for client")
	case errors.Is(err, customschema.ErrSchemaParentRetired):
		return echo.NewHTTPError(http.StatusConflict, "parent schema is retired; cannot create a new version from a retired parent")
	case errors.Is(err, customschema.ErrSchemaParentNotActive):
		return echo.NewHTTPError(http.StatusConflict, "parent schema is not the active version in its lineage")
	}
	if strings.Contains(err.Error(), validatorErrorMarker) {
		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
	}
	slog.Error("custom schema handler internal error", "error", err)
	return echo.NewHTTPError(http.StatusInternalServerError, "internal server error")
}

// schemaToResponse copies a customschema.Schema into the generated
// CustomSchemaResponse. documentCount is the live document binding count;
// CanDelete is derived from it (true iff count == 0). The model's SchemaDef
// is json.RawMessage and the generated type expects map[string]interface{},
// so we round-trip through encoding/json to reshape without losing structure.
func schemaToResponse(schema *customschema.Schema, documentCount int64) (CustomSchemaResponse, error) {
	var schemaMap map[string]interface{}
	if err := json.Unmarshal(schema.SchemaDef, &schemaMap); err != nil {
		return CustomSchemaResponse{}, err
	}
	var descriptionPtr *string
	if schema.Description != "" {
		d := schema.Description
		descriptionPtr = &d
	}
	return CustomSchemaResponse{
		Id:            openapi_types.UUID(schema.ID),
		ClientId:      schema.ClientID,
		Name:          schema.Name,
		Description:   descriptionPtr,
		Schema:        schemaMap,
		Version:       int32(schema.Version), //nolint:gosec // schema.Version is the per-lineage monotonic counter; an int32 ceiling of ~2 billion is trivially safe for schema versions
		Status:        SchemaStatus(schema.Status),
		CreatedAt:     schema.CreatedAt,
		CreatedBy:     schema.CreatedBy,
		DocumentCount: int32(documentCount), //nolint:gosec // document count per schema is bounded by total documents; int32 max (~2B) is safe
		CanDelete:     documentCount == 0,
	}, nil
}

// summaryToListRow translates a customschema.SchemaSummary into the anonymous
// row struct declared inside CustomSchemaListResponse. The alias defined
// above preserves structural identity with the generated type.
func summaryToListRow(summary customschema.SchemaSummary) customSchemaListRow {
	var descriptionPtr *string
	if summary.Schema.Description != "" {
		d := summary.Schema.Description
		descriptionPtr = &d
	}
	return customSchemaListRow{
		CanDelete:     summary.CanDelete,
		ClientId:      summary.Schema.ClientID,
		CreatedAt:     summary.Schema.CreatedAt,
		CreatedBy:     summary.Schema.CreatedBy,
		Description:   descriptionPtr,
		DocumentCount: int32(summary.DocumentCount), //nolint:gosec // documentCount is COUNT(*) of documents bound to this schema; an int32 ceiling of ~2 billion is far above any realistic per-client document count
		Id:            openapi_types.UUID(summary.Schema.ID),
		Name:          summary.Schema.Name,
		Status:        SchemaStatus(summary.Schema.Status),
		Version:       int32(summary.Schema.Version), //nolint:gosec // see schemaToResponse; per-lineage monotonic version counter
	}
}