package cabana

import (
	"fmt"
	"io/fs"
	"net/http"
	"path"
	"reflect"
	"strings"
	"time"

	"git.golem15.com/golem15/summercms/pact"
	"git.golem15.com/golem15/summercms/towel"
	"github.com/goccy/go-yaml/ast"
)

var filterScopeKeys = map[string]struct{}{
	"label": {}, "type": {}, "column": {}, "options": {},
	"modelClass": {}, "nameFrom": {}, "scope": {},
}

type filterDocument struct {
	Scopes scopeMap `yaml:"scopes"`
}

type scopeMap struct {
	items []ListFilter
}

func compileFilters(pluginID string, ctl pact.AdminController, fsys fs.FS, dir, ref string) ([]ListFilter, error) {
	file, err := filterAssetPath(pluginID, dir, ref)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), "config_filter.yaml", err)
	}
	raw, err := readAsset(fsys, file)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), file, err)
	}
	var doc filterDocument
	if err := decodeStrict(raw, &doc); err != nil {
		return nil, bootErr(pluginID, ctl.ID(), file, err)
	}
	filters := doc.Scopes.items
	if filters == nil {
		filters = []ListFilter{}
	}
	provider := filterProvider(ctl)
	for _, filter := range filters {
		if err := validateFilter(ctl, provider, filter); err != nil {
			return nil, bootErr(pluginID, ctl.ID(), file, err)
		}
	}
	return filters, nil
}

func filterAssetPath(pluginID, dir, ref string) (string, error) {
	ref = strings.TrimSpace(ref)
	if ref == "" {
		return "", fmt.Errorf("filter file is empty")
	}
	if strings.Contains(ref, "..") {
		return "", fmt.Errorf("filter path escapes the plugin")
	}
	if strings.HasPrefix(ref, "~/") || strings.Contains(ref, "/") {
		return assetPath(pluginID, ref)
	}
	return path.Join(dir, ref), nil
}

func (m *scopeMap) UnmarshalYAML(node ast.Node) error {
	node = unwrapNode(node)
	if _, ok := node.(*ast.NullNode); ok || node == nil {
		m.items = []ListFilter{}
		return nil
	}
	mapping, ok := node.(*ast.MappingNode)
	if !ok {
		return fmt.Errorf("scopes must be a mapping")
	}
	items := make([]ListFilter, 0, len(mapping.Values))
	seen := map[string]struct{}{}
	for _, entry := range mapping.Values {
		name, err := nodeString(unwrapNode(entry.Key))
		if err != nil || !identifier(name) {
			return fmt.Errorf("filter name %q is not an identifier", nodeText(entry.Key))
		}
		if _, dup := seen[name]; dup {
			return fmt.Errorf("duplicate filter %s", name)
		}
		seen[name] = struct{}{}
		filter, err := compileScopeNode(name, unwrapNode(entry.Value))
		if err != nil {
			return fmt.Errorf("filter %s: %w", name, err)
		}
		items = append(items, filter)
	}
	m.items = items
	return nil
}

func compileScopeNode(name string, node ast.Node) (ListFilter, error) {
	mapping, ok := node.(*ast.MappingNode)
	if !ok {
		return ListFilter{}, fmt.Errorf("must be a mapping")
	}
	values := map[string]ast.Node{}
	for _, entry := range mapping.Values {
		key, err := nodeString(unwrapNode(entry.Key))
		if err != nil {
			return ListFilter{}, err
		}
		if key == "conditions" {
			return ListFilter{}, fmt.Errorf("conditions is not supported; use a column or a registered model scope")
		}
		if _, known := filterScopeKeys[key]; !known {
			return ListFilter{}, fmt.Errorf("unknown field %s", key)
		}
		if _, dup := values[key]; dup {
			return ListFilter{}, fmt.Errorf("duplicate field %s", key)
		}
		values[key] = unwrapNode(entry.Value)
	}
	filter := ListFilter{Name: name}
	var err error
	if node, ok := values["label"]; ok {
		filter.Label, err = nodeString(node)
		if err != nil {
			return ListFilter{}, fmt.Errorf("label: %w", err)
		}
	}
	if node, ok := values["type"]; ok {
		filter.Type, err = nodeString(node)
		if err != nil {
			return ListFilter{}, fmt.Errorf("type: %w", err)
		}
	}
	if node, ok := values["column"]; ok {
		filter.Column, err = nodeString(node)
		if err != nil || !identifier(filter.Column) {
			return ListFilter{}, fmt.Errorf("column %q is not an identifier", filter.Column)
		}
	}
	if node, ok := values["modelClass"]; ok {
		filter.ModelClass, err = nodeString(node)
		if err != nil || strings.TrimSpace(filter.ModelClass) == "" {
			return ListFilter{}, fmt.Errorf("modelClass is empty")
		}
	}
	if node, ok := values["nameFrom"]; ok {
		filter.NameFrom, err = nodeString(node)
		if err != nil || !identifier(filter.NameFrom) {
			return ListFilter{}, fmt.Errorf("nameFrom %q is not an identifier", filter.NameFrom)
		}
	}
	if node, ok := values["scope"]; ok {
		filter.Scope, err = nodeString(node)
		if err != nil || !identifier(filter.Scope) {
			return ListFilter{}, fmt.Errorf("scope %q is not an identifier", filter.Scope)
		}
	}
	if node, ok := values["options"]; ok {
		filter.Options, err = compileFilterOptions(node)
		if err != nil {
			return ListFilter{}, fmt.Errorf("options: %w", err)
		}
	}
	if filter.Type == "" && filter.Scope != "" {
		filter.Type = "scope"
	}
	switch filter.Type {
	case "switch":
		if filter.Column == "" {
			return ListFilter{}, fmt.Errorf("column is required")
		}
		if len(filter.Options) == 0 {
			on := jsonScalar{raw: []byte("true")}
			off := jsonScalar{raw: []byte("false")}
			filter.TrueValue = &on
			filter.FalseValue = &off
		}
	case "daterange":
		if filter.Column == "" {
			return ListFilter{}, fmt.Errorf("column is required")
		}
	case "scope":
		if filter.Scope == "" || filter.ModelClass == "" || filter.NameFrom == "" {
			return ListFilter{}, fmt.Errorf("scope, modelClass, and nameFrom are required")
		}
	default:
		if filter.Type == "" {
			return ListFilter{}, fmt.Errorf("type is required")
		}
		return ListFilter{}, fmt.Errorf("unsupported filter type %s", filter.Type)
	}
	return filter, nil
}

func compileFilterOptions(node ast.Node) ([]FormOption, error) {
	mapping, ok := node.(*ast.MappingNode)
	if !ok {
		return nil, fmt.Errorf("must be a map")
	}
	options := make([]FormOption, 0, len(mapping.Values))
	for _, entry := range mapping.Values {
		value, err := nodeScalar(unwrapNode(entry.Key))
		if err != nil {
			return nil, fmt.Errorf("value: %w", err)
		}
		label, err := nodeString(unwrapNode(entry.Value))
		if err != nil {
			return nil, fmt.Errorf("label: %w", err)
		}
		options = append(options, FormOption{Value: value, Label: label})
	}
	return options, nil
}

func validateFilter(ctl pact.AdminController, provider pact.FilterScope, filter ListFilter) error {
	switch filter.Type {
	case "switch", "daterange":
		if _, _, check := listModelContract(ctl); check {
			ft, ok := modelColumnType(ctl, filter.Column)
			if !ok {
				return fmt.Errorf("column %s is not on the model", filter.Column)
			}
			if filter.Type == "switch" && !isBoolType(ft) {
				return fmt.Errorf("column %s is not a boolean", filter.Column)
			}
			if filter.Type == "daterange" && !isTimeType(ft) {
				return fmt.Errorf("column %s is not a date", filter.Column)
			}
		}
	case "scope":
		if provider == nil {
			return fmt.Errorf("scope %s requires FilterScope", filter.Scope)
		}
		registered := false
		for _, name := range provider.FilterScopes() {
			if name == filter.Scope {
				registered = true
				break
			}
		}
		if !registered {
			return fmt.Errorf("scope %s is not registered", filter.Scope)
		}
		if _, ok := provider.(pact.FilterOptions); !ok {
			return fmt.Errorf("scope filter %s needs FilterOptions on the model to serve its choices (D-27)", filter.Name)
		}
	}
	return nil
}

// FilterOption is one model-backed filter choice (D-27). Values stay the
// strings the model returns; they are sent back as filter[<name>].
type FilterOption struct {
	Value string `json:"value"`
	Label string `json:"label"`
}

// filterOptions serves GET /{vendor}/{plugin}/{controller}/filters/{scope}/options
// for a declared scope filter of the controller's list. {scope} is the filter
// name (the filter[<name>] key); the model receives the filter's scope method.
func (s *service) filterOptions(w http.ResponseWriter, r *http.Request) {
	s.protect(w, r, func(cc *CompiledController) {
		name := r.PathValue("scope")
		var filter *ListFilter
		if cc.List != nil && identifier(name) {
			for i := range cc.List.Filters {
				if cc.List.Filters[i].Name == name && cc.List.Filters[i].Type == "scope" {
					filter = &cc.List.Filters[i]
					break
				}
			}
		}
		if filter == nil {
			writeNotFound(w, r)
			return
		}
		provider, ok := filterProvider(cc.Controller).(pact.FilterOptions)
		if !ok || provider == nil {
			writeNotFound(w, r)
			return
		}
		tr := s.translator()
		locale := schemaLocale(r.Context(), tr)
		ctx := towel.WithLocale(r.Context(), locale)
		provided := provider.FilterOptions(filter.Scope)
		out := make([]FilterOption, 0, len(provided))
		for _, opt := range provided {
			out = append(out, FilterOption{Value: opt.Value, Label: translateKey(ctx, tr, opt.Label)})
		}
		WriteData(w, http.StatusOK, out, map[string]any{"locale": locale})
	})
}

func filterProvider(ctl pact.AdminController) pact.FilterScope {
	src, ok := ctl.(pact.AdminRecordSource)
	if !ok || src == nil {
		return nil
	}
	rec := src.NewRecord()
	provider, ok := rec.(pact.FilterScope)
	if !ok || provider == nil {
		return nil
	}
	return provider
}

func modelColumnType(ctl pact.AdminController, column string) (reflect.Type, bool) {
	src, ok := ctl.(pact.AdminRecordSource)
	if !ok || src == nil || src.NewRecord() == nil {
		return nil, false
	}
	t := reflect.TypeOf(src.NewRecord())
	for t != nil && t.Kind() == reflect.Pointer {
		t = t.Elem()
	}
	if t == nil || t.Kind() != reflect.Struct {
		return nil, false
	}
	for i := 0; i < t.NumField(); i++ {
		field := t.Field(i)
		if field.PkgPath != "" || isListRelation(field.Type) {
			continue
		}
		name := gormColumn(field)
		if name == "" {
			name = field.Name
		}
		if name == column {
			return field.Type, true
		}
	}
	return nil, false
}

func isTimeType(t reflect.Type) bool {
	if t == nil {
		return false
	}
	for t.Kind() == reflect.Pointer {
		t = t.Elem()
	}
	return t == reflect.TypeOf(time.Time{})
}

func isBoolType(t reflect.Type) bool {
	if t == nil {
		return false
	}
	for t.Kind() == reflect.Pointer {
		t = t.Elem()
	}
	return t.Kind() == reflect.Bool
}