package cabana

import (
	"context"
	"fmt"
	"io/fs"
	"path"
	"reflect"
	"strings"
	"time"

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

const listSearchTerm = "search"

var listColumnTypes = map[string]struct{}{
	"text": {}, "datetime": {}, "switch": {}, "date": {}, "time": {},
}

type listDocument struct {
	List             string            `yaml:"list"`
	ModelClass       string            `yaml:"modelClass"`
	Title            string            `yaml:"title"`
	RecordURL        string            `yaml:"recordUrl"`
	NoRecordsMessage string            `yaml:"noRecordsMessage"`
	RecordsPerPage   int               `yaml:"recordsPerPage"`
	PerPageOptions   []int             `yaml:"perPageOptions"`
	ShowCheckboxes   bool              `yaml:"showCheckboxes"`
	ShowSetup        bool              `yaml:"showSetup"`
	ShowSorting      *bool             `yaml:"showSorting"`
	ShowSearch       bool              `yaml:"showSearch"`
	DefaultSort      *listSortDocument `yaml:"defaultSort"`
	Toolbar          *listToolbar      `yaml:"toolbar"`
	Filter           string            `yaml:"filter"`
	Messages         *listMessageKeys  `yaml:"messages"`
	HeaderPartial    string            `yaml:"headerPartial"`
}

type listSortDocument struct {
	Column    string `yaml:"column"`
	Direction string `yaml:"direction"`
}

type listToolbar struct {
	Buttons toolbarButtons `yaml:"buttons"`
	Search  *struct {
		Prompt string `yaml:"prompt"`
		Mode   string `yaml:"mode"`
	} `yaml:"search"`
}

type columnsDocument struct {
	Columns yaml.MapSlice `yaml:"columns"`
}

type columnDocument struct {
	Label      string `yaml:"label"`
	Searchable bool   `yaml:"searchable"`
	Sortable   *bool  `yaml:"sortable"`
	Type       string `yaml:"type"`
	Relation   string `yaml:"relation"`
	Select     string `yaml:"select"`
}

// CompileListSchema compiles config_list.yaml and the columns.yaml it names.
func CompileListSchema(pluginID string, ctl pact.AdminController, fsys fs.FS) (*ListSchema, error) {
	return compileList(pluginID, ctl, fsys)
}

// CompileList compiles one controller's config_list.yaml and columns.yaml.
func CompileList(pluginID string, ctl pact.AdminController, fsys fs.FS) (*ListSchema, error) {
	return compileList(pluginID, ctl, fsys)
}

func compileList(pluginID string, ctl pact.AdminController, fsys fs.FS) (*ListSchema, error) {
	if ctl == nil {
		return nil, fmt.Errorf("cabana: admin schema %s: controller is nil", pluginID)
	}
	dir := strings.Trim(path.Clean(ctl.ConfigDir()), "/")
	if dir == "." || strings.HasPrefix(dir, "..") {
		return nil, bootErr(pluginID, ctl.ID(), ctl.ConfigDir(), fmt.Errorf("config directory escapes the plugin"))
	}
	cfgPath := path.Join(dir, "config_list.yaml")
	raw, err := readAsset(fsys, cfgPath)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, err)
	}
	var doc listDocument
	if err := decodeStrict(raw, &doc); err != nil {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, err)
	}
	if doc.ModelClass != ctl.ModelName() {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, fmt.Errorf("modelClass %q does not match %q", doc.ModelClass, ctl.ModelName()))
	}
	if strings.TrimSpace(doc.List) == "" {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, fmt.Errorf("list file is empty"))
	}
	colPath, err := assetPath(pluginID, doc.List)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, err)
	}
	columns, err := compileColumns(pluginID, ctl, fsys, colPath)
	if err != nil {
		return nil, err
	}
	per := doc.RecordsPerPage
	if per < 1 {
		per = 20
	}
	options, err := compilePageOptions(per, doc.PerPageOptions)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, err)
	}
	showSearch := doc.ShowSearch
	prompt := ""
	if doc.Toolbar != nil && doc.Toolbar.Search != nil {
		showSearch = true
		prompt = doc.Toolbar.Search.Prompt
		if mode := doc.Toolbar.Search.Mode; mode != "" && mode != "all" && mode != "any" && mode != "exact" {
			return nil, bootErr(pluginID, ctl.ID(), cfgPath, fmt.Errorf("unsupported search mode %s", mode))
		}
	}
	buttons, toolbarActions, err := compileToolbarButtons(ctl, doc.Toolbar, doc.ShowCheckboxes)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, err)
	}
	sort, err := compileDefaultSort(doc.DefaultSort, columns)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, err)
	}
	showSorting := true
	if doc.ShowSorting != nil {
		showSorting = *doc.ShowSorting
	}
	if doc.HeaderPartial != "" && !identifier(doc.HeaderPartial) {
		return nil, bootErr(pluginID, ctl.ID(), cfgPath, fmt.Errorf("headerPartial %q: %s", doc.HeaderPartial, partialPathHint))
	}
	rowActions := []RowAction{}
	if doc.RecordURL != "" {
		rowActions = append(rowActions, RowAction{
			Name:  "update",
			Label: "backend::lang.form.update",
			URL:   doc.RecordURL,
		})
	}
	bulk := []BulkAction{}
	if doc.ShowCheckboxes {
		bulk = append(bulk, BulkAction{Name: "delete", Label: "backend::lang.list.delete_selected"})
	}
	filters := []ListFilter{}
	if strings.TrimSpace(doc.Filter) != "" {
		filters, err = compileFilters(pluginID, ctl, fsys, dir, doc.Filter)
		if err != nil {
			return nil, err
		}
	}
	schema := &ListSchema{
		Title:            doc.Title,
		ModelClass:       doc.ModelClass,
		RecordURL:        doc.RecordURL,
		NoRecordsMessage: doc.NoRecordsMessage,
		RecordsPerPage:   per,
		PerPageOptions:   options,
		ShowSearch:       showSearch,
		ShowSetup:        doc.ShowSetup,
		ShowCheckboxes:   doc.ShowCheckboxes,
		ShowSorting:      showSorting,
		SearchTerm:       listSearchTerm,
		SearchPrompt:     prompt,
		DefaultSort:      sort,
		ToolbarButtons:   buttons,
		ToolbarActions:   toolbarActions,
		HeaderPartial:    doc.HeaderPartial,
		Columns:          columns,
		Filters:          filters,
		RowActions:       rowActions,
		BulkActions:      bulk,
	}
	if doc.Messages != nil {
		schema.messageKeys = *doc.Messages
	}
	keys := localizeMessages[listMessageKeys, ListMessages](context.Background(), nil, schema.listMessageKeySet())
	schema.Messages = &keys
	return schema, nil
}

func compileColumns(pluginID string, ctl pact.AdminController, fsys fs.FS, colPath string) ([]ListColumn, error) {
	colRaw, err := readAsset(fsys, colPath)
	if err != nil {
		return nil, bootErr(pluginID, ctl.ID(), colPath, err)
	}
	var cols columnsDocument
	if err := decodeStrict(colRaw, &cols); err != nil {
		return nil, bootErr(pluginID, ctl.ID(), colPath, err)
	}
	modelCols, modelRels, checkModel := listModelContract(ctl)
	compiled := make([]ListColumn, 0, len(cols.Columns))
	seen := map[string]struct{}{}
	for _, item := range cols.Columns {
		key, ok := item.Key.(string)
		if !ok || !identifier(key) {
			return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("column key %v is not an identifier", item.Key))
		}
		if _, dup := seen[key]; dup {
			return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("duplicate column %s", key))
		}
		seen[key] = struct{}{}
		encoded, err := yaml.Marshal(item.Value)
		if err != nil {
			return nil, bootErr(pluginID, ctl.ID(), colPath, err)
		}
		var spec columnDocument
		if err := decodeStrict(encoded, &spec); err != nil {
			return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("column %s: %w", key, err))
		}
		if spec.Type != "" {
			if _, known := listColumnTypes[spec.Type]; !known {
				return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("unsupported column type %s", spec.Type))
			}
		}
		if spec.Relation != "" || spec.Select != "" {
			if !identifier(spec.Relation) {
				return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("relation %q is not an identifier", spec.Relation))
			}
			if !identifier(spec.Select) {
				return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("select %q is not an identifier", spec.Select))
			}
			if checkModel {
				if _, known := modelRels[spec.Relation]; !known {
					return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("relation %s is not on the model", spec.Relation))
				}
			}
		} else if checkModel {
			if _, known := modelCols[key]; !known {
				return nil, bootErr(pluginID, ctl.ID(), colPath, fmt.Errorf("column %s is not on the model", key))
			}
		}
		sortable := spec.Relation == ""
		if spec.Sortable != nil {
			sortable = *spec.Sortable
		}
		compiled = append(compiled, ListColumn{
			Key:        key,
			Label:      spec.Label,
			Searchable: spec.Searchable,
			Sortable:   sortable,
			Type:       spec.Type,
			Relation:   spec.Relation,
			Select:     spec.Select,
		})
	}
	return compiled, nil
}

func compilePageOptions(recordsPerPage int, declared []int) ([]int, error) {
	if len(declared) == 0 {
		return []int{recordsPerPage}, nil
	}
	options := make([]int, len(declared))
	seen := map[int]struct{}{}
	found := false
	for i, n := range declared {
		if n < 1 {
			return nil, fmt.Errorf("perPageOptions must be positive")
		}
		if _, dup := seen[n]; dup {
			return nil, fmt.Errorf("duplicate perPageOptions %d", n)
		}
		seen[n] = struct{}{}
		options[i] = n
		if n == recordsPerPage {
			found = true
		}
	}
	if !found {
		return nil, fmt.Errorf("recordsPerPage %d is not in perPageOptions", recordsPerPage)
	}
	return options, nil
}

// toolbarButtons is the declarative toolbar.buttons list (D-14, D-12):
// action names in display order. The built-in create and delete sit next to
// names the controller registers through pact.HasAdminActions; decode has no
// controller, so membership is resolved in compileToolbarButtons. A scalar
// (Winter's partial name) is rejected with a pointer at the list syntax.
type toolbarButtons struct {
	items []string
}

func (b *toolbarButtons) UnmarshalYAML(node ast.Node) error {
	node = unwrapNode(node)
	switch n := node.(type) {
	case nil, *ast.NullNode:
		b.items = nil
		return nil
	case *ast.SequenceNode:
		values := sequenceValues(n)
		items := make([]string, 0, len(values))
		seen := map[string]struct{}{}
		for _, item := range values {
			action, err := nodeString(unwrapNode(item))
			if err != nil {
				return fmt.Errorf("toolbar.buttons entries must be action names")
			}
			if _, dup := seen[action]; dup {
				return fmt.Errorf("toolbar.buttons: duplicate action %s", action)
			}
			seen[action] = struct{}{}
			items = append(items, action)
		}
		b.items = items
		return nil
	default:
		return fmt.Errorf("toolbar.buttons must be a list of actions (create, delete or registered actions); the Winter partial %q is not supported", nodeText(node))
	}
}

// compileToolbarButtons resolves every toolbar.buttons name against the
// built-in create and delete and the controller's registered actions: the one
// action namespace widgets use too. It returns the names in declared order and
// the registered entries with their (source) labels.
func compileToolbarButtons(ctl pact.AdminController, toolbar *listToolbar, showCheckboxes bool) ([]string, []ToolbarAction, error) {
	if toolbar == nil || len(toolbar.Buttons.items) == 0 {
		return []string{}, []ToolbarAction{}, nil
	}
	registered := map[string]pact.AdminAction{}
	if src, ok := ctl.(pact.HasAdminActions); ok && src != nil {
		for _, action := range src.AdminActions() {
			registered[action.Name] = action
		}
	}
	out := append([]string(nil), toolbar.Buttons.items...)
	custom := []ToolbarAction{}
	for _, name := range out {
		if builtinToolbarActions[name] {
			if name == "delete" && !showCheckboxes {
				return nil, nil, fmt.Errorf("toolbar.buttons: delete needs showCheckboxes: true")
			}
			continue
		}
		action, ok := registered[name]
		if !ok {
			return nil, nil, fmt.Errorf("toolbar.buttons: unsupported action %s (want create, delete or an action the controller registers)", name)
		}
		if strings.TrimSpace(action.Label) == "" {
			return nil, nil, fmt.Errorf("toolbar.buttons: action %s needs a label", name)
		}
		custom = append(custom, ToolbarAction{Name: name, Label: action.Label})
	}
	return out, custom, nil
}

func compileDefaultSort(doc *listSortDocument, columns []ListColumn) (*ListSort, error) {
	if doc == nil {
		return nil, nil
	}
	var match *ListColumn
	for i := range columns {
		if columns[i].Key == doc.Column {
			match = &columns[i]
			break
		}
	}
	if match == nil {
		return nil, fmt.Errorf("default sort column %s is not a list column", doc.Column)
	}
	if !match.Sortable {
		return nil, fmt.Errorf("default sort column %s is not sortable", doc.Column)
	}
	if doc.Direction != "asc" && doc.Direction != "desc" {
		return nil, fmt.Errorf("default sort direction %s must be asc or desc", doc.Direction)
	}
	return &ListSort{Column: doc.Column, Direction: doc.Direction}, nil
}

func listModelContract(ctl pact.AdminController) (map[string]struct{}, map[string]struct{}, bool) {
	src, ok := ctl.(pact.AdminRecordSource)
	if !ok || src == nil {
		return nil, nil, false
	}
	model := src.NewRecord()
	if model == nil {
		return nil, nil, false
	}
	t := reflect.TypeOf(model)
	for t != nil && t.Kind() == reflect.Pointer {
		t = t.Elem()
	}
	if t == nil || t.Kind() != reflect.Struct {
		return nil, nil, false
	}
	cols := map[string]struct{}{}
	rels := map[string]struct{}{}
	for _, mf := range modelFields(t) {
		field := mf.Field
		if isListRelation(field.Type) {
			rels[field.Name] = struct{}{}
			// Winter YAML spells relations in lowercase (relation: genre)
			// while the Go field is exported (Genre).
			rels[strings.ToLower(field.Name)] = struct{}{}
			continue
		}
		name := gormColumn(field)
		if name == "" {
			name = field.Name
		}
		cols[name] = struct{}{}
	}
	return cols, rels, true
}

func isListRelation(t reflect.Type) bool {
	for t.Kind() == reflect.Pointer {
		t = t.Elem()
	}
	if t.Kind() == reflect.Slice {
		t = t.Elem()
		for t.Kind() == reflect.Pointer {
			t = t.Elem()
		}
	}
	if t.Kind() != reflect.Struct {
		return false
	}
	if t == reflect.TypeOf(time.Time{}) {
		return false
	}
	if t == reflect.TypeOf(gorm.DeletedAt{}) {
		return false
	}
	// A struct stored in one column (it scans or values itself, such as
	// lagoon.Date and lagoon.TimeOfDay) is a scalar, not a relation.
	if reflect.PointerTo(t).Implements(scannerType) || t.Implements(valuerType) || reflect.PointerTo(t).Implements(valuerType) {
		return false
	}
	return true
}

// Localize copies the cached list schema and resolves display strings for one request.
// Column, filter, and scope identifiers and option values are not translated.
func (s *ListSchema) Localize(ctx context.Context, tr *phrasebook.Translator) (*ListSchema, error) {
	if s == nil {
		return nil, fmt.Errorf("cabana: nil list schema")
	}
	if ctx == nil {
		ctx = context.Background()
	}
	locale := schemaLocale(ctx, tr)
	ctx = towel.WithLocale(ctx, locale)
	out := *s
	out.Title = translateKey(ctx, tr, s.Title)
	out.NoRecordsMessage = translateKey(ctx, tr, s.NoRecordsMessage)
	out.SearchPrompt = translateKey(ctx, tr, s.SearchPrompt)
	out.PerPageOptions = append([]int(nil), s.PerPageOptions...)
	out.ToolbarButtons = append([]string(nil), s.ToolbarButtons...)
	out.ToolbarActions = make([]ToolbarAction, len(s.ToolbarActions))
	for i, action := range s.ToolbarActions {
		action.Label = translateKey(ctx, tr, action.Label)
		out.ToolbarActions[i] = action
	}
	out.Assets = ControllerAssets{
		Scripts: append([]string{}, s.Assets.Scripts...),
		Styles:  append([]string{}, s.Assets.Styles...),
	}
	if s.DefaultSort != nil {
		sort := *s.DefaultSort
		out.DefaultSort = &sort
	}
	out.Columns = localizeListColumns(ctx, tr, s.Columns)
	out.Filters = localizeListFilters(ctx, tr, s.Filters)
	out.RowActions = localizeRowActions(ctx, tr, s.RowActions)
	out.BulkActions = localizeBulkActions(ctx, tr, s.BulkActions)
	messages := localizeMessages[listMessageKeys, ListMessages](ctx, tr, s.listMessageKeySet())
	out.Messages = &messages
	out.Meta = &FormMeta{Locale: locale}
	return &out, nil
}

func localizeListColumns(ctx context.Context, tr *phrasebook.Translator, cols []ListColumn) []ListColumn {
	out := make([]ListColumn, len(cols))
	for i, col := range cols {
		col.Label = translateKey(ctx, tr, col.Label)
		out[i] = col
	}
	if out == nil {
		out = []ListColumn{}
	}
	return out
}

func localizeListFilters(ctx context.Context, tr *phrasebook.Translator, filters []ListFilter) []ListFilter {
	out := make([]ListFilter, len(filters))
	for i, filter := range filters {
		filter.Label = translateKey(ctx, tr, filter.Label)
		if len(filter.Options) > 0 {
			opts := make([]FormOption, len(filter.Options))
			for j, opt := range filter.Options {
				opt.Label = translateKey(ctx, tr, opt.Label)
				opts[j] = opt
			}
			filter.Options = opts
		}
		out[i] = filter
	}
	if out == nil {
		out = []ListFilter{}
	}
	return out
}

func localizeRowActions(ctx context.Context, tr *phrasebook.Translator, actions []RowAction) []RowAction {
	out := make([]RowAction, len(actions))
	for i, action := range actions {
		action.Label = translateKey(ctx, tr, action.Label)
		out[i] = action
	}
	if out == nil {
		out = []RowAction{}
	}
	return out
}

func localizeBulkActions(ctx context.Context, tr *phrasebook.Translator, actions []BulkAction) []BulkAction {
	out := make([]BulkAction, len(actions))
	for i, action := range actions {
		action.Label = translateKey(ctx, tr, action.Label)
		out[i] = action
	}
	if out == nil {
		out = []BulkAction{}
	}
	return out
}