package shared

import (
	"encoding/json"
	"fmt"
	"regexp"
	"strings"

	"bookra/apps/backend/internal/domain"
)

var intakeKeyRe = regexp.MustCompile(`[^a-z0-9]+`)

// ParseIntakeFields decodes the stored JSON list of declared intake fields;
// empty or corrupt values decode to nil so a bad row cannot break listing.
func ParseIntakeFields(raw string) []domain.IntakeField {
	if raw == "" || raw == "[]" {
		return nil
	}
	var fields []domain.IntakeField
	if err := json.Unmarshal([]byte(raw), &fields); err != nil {
		return nil
	}
	return fields
}

// IntakeLabels maps a service's declared intake field keys to their display
// labels, so booking views can render questions rather than slugs.
func IntakeLabels(raw string) map[string]string {
	fields := ParseIntakeFields(raw)
	if len(fields) == 0 {
		return nil
	}
	labels := make(map[string]string, len(fields))
	for _, field := range fields {
		labels[field.Key] = field.Label
	}
	return labels
}

// NormalizeIntakeFields validates a service's declared intake fields and
// returns the canonical JSON string for storage. Keys are slugified from the
// provided key or the label, must be unique, and fields are capped at 8.
// Returns the wrapped error unchanged when it is already an app error.
func NormalizeIntakeFields(fields []domain.IntakeField) (string, error) {
	if len(fields) == 0 {
		return "[]", nil
	}
	if len(fields) > 8 {
		return "", fmt.Errorf("intakeFields supports at most 8 fields")
	}
	seen := make(map[string]bool, len(fields))
	out := make([]domain.IntakeField, 0, len(fields))
	for _, f := range fields {
		label := strings.TrimSpace(f.Label)
		if len(label) < 1 || len(label) > 80 {
			return "", fmt.Errorf("intake field label must be 1-80 characters")
		}
		ftype := strings.ToLower(strings.TrimSpace(f.Type))
		if ftype != "text" && ftype != "yesno" {
			return "", fmt.Errorf("intake field type must be text or yesno")
		}
		key := strings.TrimSpace(f.Key)
		if key == "" {
			key = label
		}
		key = strings.Trim(intakeKeyRe.ReplaceAllString(strings.ToLower(key), "_"), "_")
		if key == "" || len(key) > 40 {
			return "", fmt.Errorf("intake field key must be 1-40 slug characters")
		}
		if seen[key] {
			return "", fmt.Errorf("duplicate intake field key %q", key)
		}
		seen[key] = true
		out = append(out, domain.IntakeField{Key: key, Label: label, Type: ftype, Required: f.Required})
	}
	raw, err := json.Marshal(out)
	if err != nil {
		return "", err
	}
	return string(raw), nil
}

// ParseIntakeAnswers decodes a booking's stored intake JSON object; empty or
// corrupt values decode to nil.
func ParseIntakeAnswers(raw string) map[string]string {
	if raw == "" || raw == "{}" {
		return nil
	}
	var answers map[string]string
	if err := json.Unmarshal([]byte(raw), &answers); err != nil {
		return nil
	}
	return answers
}

// NormalizeIntakeAnswers validates a customer's intake answers against the
// service's declared fields and returns the canonical JSON object. Required
// fields must be present and non-empty; yesno coerces to "yes"/"no"; text is
// trimmed and capped at 500 chars. Only declared keys are stored — unknown
// keys are dropped rather than persisted.
func NormalizeIntakeAnswers(fields []domain.IntakeField, intake map[string]string) (string, error) {
	if len(fields) == 0 {
		return "{}", nil
	}
	out := make(map[string]string, len(fields))
	for _, f := range fields {
		raw, ok := intake[f.Key]
		value := strings.TrimSpace(raw)
		if !ok || value == "" {
			if f.Required {
				return "", fmt.Errorf("intake field %q is required", f.Label)
			}
			continue
		}
		switch f.Type {
		case "yesno":
			switch strings.ToLower(value) {
			case "yes", "ano", "true", "1":
				value = "yes"
			case "no", "ne", "false", "0":
				value = "no"
			default:
				return "", fmt.Errorf("intake field %q must be yes or no", f.Label)
			}
		default:
			if len(value) > 500 {
				return "", fmt.Errorf("intake field %q must be at most 500 characters", f.Label)
			}
		}
		out[f.Key] = value
	}
	raw, err := json.Marshal(out)
	if err != nil {
		return "", err
	}
	return string(raw), nil
}