package parse

import (
	"fmt"
	"strconv"
	"strings"
)

type Result struct {
	Body       string
	Glyph      string
	TimeAnchor *string
	Tags       []string
	CardSuffix *string
}

var validCardTypes = map[string]string{
	"card":      "snippet",
	"c":         "snippet",
	"snippet":   "snippet",
	"template":  "template",
	"checklist": "checklist",
	"decision":  "decision",
	"link":      "link",
}

func Parse(input string) (*Result, error) {
	input = strings.TrimSpace(input)
	if input == "" {
		return nil, fmt.Errorf("empty input")
	}

	r := &Result{
		Glyph: "note",
		Tags:  []string{},
	}

	tokens := strings.Fields(input)
	if len(tokens) == 0 {
		return nil, fmt.Errorf("empty input")
	}

	first := tokens[0]
	switch first {
	case "-", "▸":
		r.Glyph = "todo"
		tokens = tokens[1:]
	case "*", "◇":
		r.Glyph = "event"
		tokens = tokens[1:]
	}

	var bodyParts []string
	seen := map[string]bool{}

	for _, tok := range tokens {
		switch {
		case strings.HasPrefix(tok, "@") && len(tok) > 1:
			timeStr := tok[1:]
			if err := validateTime(timeStr); err != nil {
				return nil, fmt.Errorf("invalid time %q: %w", timeStr, err)
			}
			if r.TimeAnchor != nil {
				return nil, fmt.Errorf("multiple time anchors")
			}
			r.TimeAnchor = &timeStr

		case strings.HasPrefix(tok, "#") && len(tok) > 1:
			tag := tok[1:]
			if !seen[tag] {
				r.Tags = append(r.Tags, tag)
				seen[tag] = true
			}

		case strings.HasPrefix(tok, "^") && len(tok) > 1:
			suffix := tok[1:]
			cardType, ok := validCardTypes[suffix]
			if !ok {
				return nil, fmt.Errorf("invalid card type %q", suffix)
			}
			if r.CardSuffix != nil {
				return nil, fmt.Errorf("multiple card suffixes")
			}
			r.CardSuffix = &cardType

		default:
			bodyParts = append(bodyParts, tok)
		}
	}

	r.Body = strings.Join(bodyParts, " ")
	if r.Body == "" {
		return nil, fmt.Errorf("empty body after extracting modifiers")
	}

	return r, nil
}

func validateTime(s string) error {
	parts := strings.SplitN(s, ":", 2)
	if len(parts) != 2 {
		return fmt.Errorf("expected HH:MM format")
	}
	h, err := strconv.Atoi(parts[0])
	if err != nil || h < 0 || h > 23 {
		return fmt.Errorf("hours must be 0-23")
	}
	m, err := strconv.Atoi(parts[1])
	if err != nil || m < 0 || m > 59 {
		return fmt.Errorf("minutes must be 0-59")
	}
	return nil
}