package cabana

import (
	"context"
	"database/sql/driver"
	"encoding/json"
	"fmt"
	"math"
	"reflect"
	"strconv"
	"strings"

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

// repeaterType is the core list-of-rows field type (D-07).
const repeaterType = "repeater"

// The phrase keys of the repeater's row count messages (backend::lang).
const (
	msgRepeaterMaxItems = "backend::lang.repeater.max_items"
	msgRepeaterMinItems = "backend::lang.repeater.min_items"
)

// repeaterKeys are the fields.yaml keys a repeater field accepts.
var repeaterKeys = map[string]bool{
	"label": true, "comment": true, "span": true, "type": true, "required": true,
	"tab": true, "context": true, "prompt": true,
	"maxItems": true, "minItems": true, "titleFrom": true, "form": true,
}

// repeaterOnlyKeys are valid on type repeater only.
var repeaterOnlyKeys = []string{"form", "maxItems", "minItems", "titleFrom"}

// repeaterNestedTypes are the field types a repeater row may hold.
var repeaterNestedTypes = map[string]bool{
	"text": true, "textarea": true, "number": true, "checkbox": true,
	"switch": true, "dropdown": true, richEditorType: true,
}

// compileRepeater decodes a `type: repeater` field: its nested form.fields
// (compiled with the rules of top-level fields, restricted to
// repeaterNestedTypes), prompt, maxItems, minItems and titleFrom. WinterCMS's
// groups and style are refused loudly on any field, the repeater-only keys on
// any other type. The span is always full.
func compileRepeater(name, typ string, values map[string]ast.Node, field *FormField) error {
	if _, ok := values["groups"]; ok {
		return fmt.Errorf("repeater groups are not supported")
	}
	if _, ok := values["style"]; ok {
		return fmt.Errorf("repeater style is not supported")
	}
	if typ != repeaterType {
		for _, key := range repeaterOnlyKeys {
			if _, ok := values[key]; ok {
				return fmt.Errorf("%s is only valid on type: repeater", key)
			}
		}
		return nil
	}
	for key := range values {
		if !repeaterKeys[key] {
			return fmt.Errorf("%s is not valid on type: repeater", key)
		}
	}
	field.Span = "full"
	if node, ok := values["prompt"]; ok {
		prompt, err := nodeString(node)
		if err != nil {
			return fmt.Errorf("prompt: %w", err)
		}
		field.Prompt = prompt
	}
	formNode, ok := values["form"].(*ast.MappingNode)
	if !ok {
		return fmt.Errorf("a repeater needs form: with fields")
	}
	var fieldsNode ast.Node
	for _, entry := range formNode.Values {
		key, err := nodeString(unwrapNode(entry.Key))
		if err != nil {
			return fmt.Errorf("form: %w", err)
		}
		switch key {
		case "fields":
			fieldsNode = unwrapNode(entry.Value)
		case "groups":
			return fmt.Errorf("repeater groups are not supported")
		default:
			return fmt.Errorf("form: unknown field %s (a repeater form takes fields only)", key)
		}
	}
	if fieldsNode == nil {
		return fmt.Errorf("a repeater needs form: with fields")
	}
	nested, err := decodeFieldMapping(fieldsNode, nil, nil)
	if err != nil {
		return fmt.Errorf("repeater %s: %w", name, err)
	}
	if len(nested) == 0 {
		return fmt.Errorf("repeater %s: form.fields is empty", name)
	}
	for _, inner := range nested {
		if !repeaterNestedTypes[inner.Type] {
			return fmt.Errorf("repeater %s: field %s: type %s is not supported in a repeater (want text, textarea, number, checkbox, switch, dropdown or richeditor)", name, inner.Name, inner.Type)
		}
		if inner.Tab != "" || inner.Context != nil || inner.Preset != nil {
			return fmt.Errorf("repeater %s: field %s: tab, context and preset are not supported in a repeater row", name, inner.Name)
		}
	}
	if err := checkDependsOn(nested, name); err != nil {
		return err
	}
	field.Form = &RepeaterForm{Fields: nested}
	for _, key := range []string{"maxItems", "minItems"} {
		node, ok := values[key]
		if !ok {
			continue
		}
		n, err := nodeNonNegativeInt(node)
		if err != nil {
			return fmt.Errorf("%s: %w", key, err)
		}
		if key == "maxItems" {
			field.MaxItems = &n
		} else {
			field.MinItems = &n
		}
	}
	if field.MinItems != nil && field.MaxItems != nil && *field.MinItems > *field.MaxItems {
		return fmt.Errorf("minItems %d is greater than maxItems %d", *field.MinItems, *field.MaxItems)
	}
	if node, ok := values["titleFrom"]; ok {
		title, err := nodeString(node)
		if err != nil {
			return fmt.Errorf("titleFrom: %w", err)
		}
		found := false
		for _, inner := range nested {
			found = found || inner.Name == title
		}
		if !found {
			return fmt.Errorf("titleFrom %s is not a field of the repeater form", title)
		}
		field.TitleFrom = title
	}
	return nil
}

func nodeNonNegativeInt(node ast.Node) (int, error) {
	n, ok := unwrapNode(node).(*ast.IntegerNode)
	if !ok {
		return 0, fmt.Errorf("want a non-negative integer")
	}
	var v int64
	switch t := n.Value.(type) {
	case int64:
		v = t
	case uint64:
		if t > math.MaxInt32 {
			return 0, fmt.Errorf("want a non-negative integer")
		}
		v = int64(t)
	case int:
		v = int64(t)
	default:
		return 0, fmt.Errorf("want a non-negative integer")
	}
	if v < 0 || v > math.MaxInt32 {
		return 0, fmt.Errorf("want a non-negative integer")
	}
	return int(v), nil
}

// repeaterNames is the set of the controller form's repeater field names.
func repeaterNames(cc *CompiledController) map[string]bool {
	if cc == nil || cc.Form == nil {
		return nil
	}
	var out map[string]bool
	for _, field := range cc.Form.Fields {
		if field.Type == repeaterType {
			if out == nil {
				out = map[string]bool{}
			}
			out[field.Name] = true
		}
	}
	return out
}

// listValue reports whether v is a JSON list.
func listValue(v any) bool {
	_, ok := v.([]any)
	return ok
}

// liftRepeaterValues decodes every submitted repeater value of the form in
// place, before the scalar projection: null becomes an empty list; a list
// must hold objects, and each row keeps only the nested field names, with its
// scalars coerced per nested type (number to a JSON number, checkbox and
// switch to a boolean, the rest to a string or null). A required nested value
// missing from a row is a 422 under field.index.nested; a row count above
// maxItems or below minItems is a 422 on the field; any other shape is a 422
// on the field. A required repeater needs at least one row when it is
// submitted, and on create also when it is not.
func liftRepeaterValues(ctx context.Context, cc *CompiledController, body map[string]any, op string, tr *phrasebook.Translator) error {
	if cc == nil || cc.Form == nil || body == nil {
		return nil
	}
	ctx = towel.WithLocale(ctx, schemaLocale(ctx, tr))
	details := map[string]any{}
	for _, field := range cc.Form.Fields {
		if field.Type != repeaterType || !contextAllows(cc, field.Name, op) {
			continue
		}
		raw, present := body[field.Name]
		if !present {
			if field.Required && op == "create" {
				details[field.Name] = []string{"The " + field.Name + " field is required."}
			}
			continue
		}
		var items []any
		switch v := raw.(type) {
		case nil:
			items = []any{}
		case []any:
			items = v
		default:
			details[field.Name] = []string{"The " + field.Name + " field must be a list of rows."}
			continue
		}
		rows := make([]any, 0, len(items))
		shapeOK := true
		for i, item := range items {
			row, ok := item.(map[string]any)
			if !ok {
				shapeOK = false
				break
			}
			clean, errs := decodeRepeaterRow(field, i, row)
			for key, msg := range errs {
				details[key] = []string{msg}
			}
			rows = append(rows, clean)
		}
		if !shapeOK {
			details[field.Name] = []string{"The " + field.Name + " field must be a list of rows."}
			continue
		}
		switch {
		case field.Required && len(rows) == 0:
			details[field.Name] = []string{"The " + field.Name + " field is required."}
		case field.MaxItems != nil && len(rows) > *field.MaxItems:
			details[field.Name] = []string{trParams(ctx, tr, msgRepeaterMaxItems, map[string]string{"max": strconv.Itoa(*field.MaxItems)})}
		case field.MinItems != nil && len(rows) < *field.MinItems:
			details[field.Name] = []string{trParams(ctx, tr, msgRepeaterMinItems, map[string]string{"min": strconv.Itoa(*field.MinItems)})}
		}
		body[field.Name] = rows
	}
	if len(details) > 0 {
		return &ValidationError{Details: details}
	}
	return nil
}

// trParams translates key with params, or keeps the key without a
// translator.
func trParams(ctx context.Context, tr *phrasebook.Translator, key string, params map[string]string) string {
	if tr == nil {
		return key
	}
	return tr.Get(ctx, key, params)
}

// decodeRepeaterRow keeps the nested fields of one submitted row, coerced per
// type, and reports the row's errors keyed field.index.nested.
func decodeRepeaterRow(field FormField, index int, row map[string]any) (map[string]any, map[string]string) {
	out := make(map[string]any, len(field.Form.Fields))
	errs := map[string]string{}
	for _, inner := range field.Form.Fields {
		path := fmt.Sprintf("%s.%d.%s", field.Name, index, inner.Name)
		value, err := coerceRowValue(inner.Type, row[inner.Name])
		if err != nil {
			errs[path] = "The " + path + " field " + err.Error() + "."
			continue
		}
		if inner.Required && blankValue(value) {
			errs[path] = "The " + path + " field is required."
		}
		out[inner.Name] = value
	}
	return out, errs
}

// coerceRowValue turns a submitted nested value into what a row stores for
// typ.
func coerceRowValue(typ string, v any) (any, error) {
	switch typ {
	case "checkbox", "switch":
		switch t := v.(type) {
		case nil:
			return false, nil
		case bool:
			return t, nil
		case string:
			switch strings.ToLower(strings.TrimSpace(t)) {
			case "1", "true", "on", "yes":
				return true, nil
			case "", "0", "false", "off", "no":
				return false, nil
			}
		case json.Number:
			return t.String() != "0", nil
		case float64:
			return t != 0, nil
		}
		return nil, fmt.Errorf("must be true or false")
	case "number":
		switch t := v.(type) {
		case nil:
			return nil, nil
		case json.Number:
			return t, nil
		case float64:
			return json.Number(strconv.FormatFloat(t, 'f', -1, 64)), nil
		case int:
			return json.Number(strconv.Itoa(t)), nil
		case string:
			s := strings.TrimSpace(t)
			if s == "" {
				return nil, nil
			}
			if _, err := strconv.ParseFloat(s, 64); err == nil {
				return json.Number(s), nil
			}
		}
		return nil, fmt.Errorf("must be a number")
	default:
		switch t := v.(type) {
		case nil:
			return nil, nil
		case string:
			return t, nil
		case json.Number:
			return t.String(), nil
		case float64:
			return strconv.FormatFloat(t, 'f', -1, 64), nil
		case bool:
			return strconv.FormatBool(t), nil
		}
		return nil, fmt.Errorf("must be text")
	}
}

func blankValue(v any) bool {
	switch t := v.(type) {
	case nil:
		return true
	case string:
		return strings.TrimSpace(t) == ""
	}
	return false
}

// repeaterRows is the projected rows of a repeater field, or false.
func repeaterRows(projected map[string]any, key string) ([]any, bool) {
	v, ok := projected[key]
	if !ok {
		return nil, false
	}
	rows, ok := v.([]any)
	return rows, ok
}

// sanitizeRepeaterRichEditors runs every nested richeditor value of the
// projected repeater rows through seaglass, so no row stores unsanitized
// HTML, and reports removals under field.index.nested.
func sanitizeRepeaterRichEditors(cc *CompiledController, projected map[string]any) []pluginNotice {
	if cc == nil || cc.Form == nil {
		return nil
	}
	var notices []pluginNotice
	for _, field := range cc.Form.Fields {
		if field.Type != repeaterType || field.Form == nil {
			continue
		}
		rows, ok := repeaterRows(projected, fillKeyOf(cc, field.Name))
		if !ok {
			continue
		}
		for i, item := range rows {
			row, ok := item.(map[string]any)
			if !ok {
				continue
			}
			for _, inner := range field.Form.Fields {
				if inner.Type != richEditorType {
					continue
				}
				text, ok := row[inner.Name].(string)
				if !ok {
					continue
				}
				clean, report := seaglass.SanitizeReport(text)
				row[inner.Name] = clean
				path := fmt.Sprintf("%s.%d.%s", field.Name, i, inner.Name)
				for _, notice := range richEditorNotices(report) {
					notices = append(notices, pluginNotice{field: path, notice: notice})
				}
			}
		}
	}
	return notices
}

// hydrateRepeaterFields replaces the stored value of every repeater field in
// a record response with its list of rows: a lagoon.Jsonable column (or any
// driver.Valuer) is decoded from its JSON text, any other value through a
// JSON round trip. A missing or null value is an empty list.
func hydrateRepeaterFields(cc *CompiledController, data map[string]any) {
	if cc == nil || cc.Form == nil || data == nil {
		return
	}
	for _, field := range cc.Form.Fields {
		if field.Type != repeaterType {
			continue
		}
		value, ok := data[field.Name]
		if !ok {
			continue
		}
		data[field.Name] = storedRows(value)
	}
}

func storedRows(value any) []any {
	rows := []any{}
	raw, ok := storedJSON(value)
	if !ok {
		return rows
	}
	var decoded []any
	if err := json.Unmarshal(raw, &decoded); err != nil || decoded == nil {
		return rows
	}
	return decoded
}

// storedJSON is the JSON text of a stored repeater value: a text column's
// string, a driver.Valuer's text (lagoon.Jsonable), or any other value
// marshaled. It is false for a missing or null value.
func storedJSON(value any) ([]byte, bool) {
	switch t := value.(type) {
	case nil:
		return nil, false
	case string:
		return []byte(t), true
	case *string:
		if t == nil {
			return nil, false
		}
		return []byte(*t), true
	case driver.Valuer:
		v, err := t.Value()
		if err != nil || v == nil {
			return nil, false
		}
		switch text := v.(type) {
		case []byte:
			return text, true
		case string:
			return []byte(text), true
		}
		return nil, false
	}
	rv := reflect.ValueOf(value)
	if rv.Kind() == reflect.Pointer && rv.IsNil() {
		return nil, false
	}
	b, err := json.Marshal(value)
	return b, err == nil
}