package main

import (
	"crypto/sha256"
	"encoding/hex"
	"regexp"
	"strings"
)

// Question is an interactive prompt detected on the agent's screen:
// tool approval ("Do you want to proceed?"), folder trust, ask_question
// multiple choice, auth pickers etc.
type Question struct {
	Text     string   `json:"text"`
	Options  []Option `json:"options"`
	Selected int      `json:"selected"` // index of the ">"-marked row, -1 if unknown
	Numbered bool     `json:"numbered"` // options can be picked with digit keys
	Hash     string   `json:"hash"`     // stable id: same question => same hash
}

type Option struct {
	Num   int    `json:"num"` // 1-based number if the list is numbered, else 0
	Label string `json:"label"`
}

var (
	numberedRe = regexp.MustCompile(`^\s*(?:[>●○]\s*)?(\d+)\.\s+(.+?)\s*$`)
	selectedRe = regexp.MustCompile(`^\s*>\s+(\S.*?)\s*$`)
	indentedRe = regexp.MustCompile(`^\s{2,}(\S.*?)\s*$`)
	hintRe     = regexp.MustCompile(`↑/↓|↵|esc to|ctrl\+|tab Amend|enter Confirm|Navigate|\? for shortcuts|Use Enter to select`)
	borderRe   = regexp.MustCompile(`^[\s│╭╰╮╯]+|[\s│╭╰╮╯]+$`)
)

func cleanLine(l string) string {
	return borderRe.ReplaceAllString(l, "")
}

func isHint(l string) bool { return hintRe.MatchString(l) }

// optionish reports whether a raw line can belong to an option block.
func optionish(raw string) bool {
	c := cleanLine(raw)
	if c == "" || isHint(c) {
		return false
	}
	return numberedRe.MatchString(c) || selectedRe.MatchString(c) || indentedRe.MatchString(raw)
}

// DetectQuestion scans the tail of a pane capture for a pending
// interactive question. Returns nil when the agent is not asking.
func DetectQuestion(screen string) *Question {
	lines := strings.Split(strings.TrimRight(screen, "\n"), "\n")
	if len(lines) > 45 {
		lines = lines[len(lines)-45:]
	}

	// Anchor: the last line that is a numbered option or a ">" selection.
	anchor := -1
	for i := len(lines) - 1; i >= 0; i-- {
		c := cleanLine(lines[i])
		if c == "" || isHint(c) {
			continue
		}
		if numberedRe.MatchString(c) || selectedRe.MatchString(c) {
			anchor = i
			break
		}
	}
	if anchor < 0 {
		return nil
	}

	// Grow the block over contiguous option-ish lines. Long numbered
	// labels wrap to column 0 in the TUI, so bridge over up to 3
	// non-matching lines when another option row lies beyond them.
	start, end := anchor, anchor
	for i := start - 1; i >= 0; i-- {
		if optionish(lines[i]) {
			start = i
			continue
		}
		c := cleanLine(lines[i])
		if c == "" || isHint(c) {
			break
		}
		bridged := false
		for k := i - 1; k >= i-3 && k >= 0; k-- {
			if numberedRe.MatchString(cleanLine(lines[k])) {
				start, i, bridged = k, k, true
				break
			}
		}
		if !bridged {
			break
		}
	}
	for i := end + 1; i < len(lines); i++ {
		if optionish(lines[i]) {
			end = i
			continue
		}
		c := cleanLine(lines[i])
		if c == "" || isHint(c) {
			break
		}
		bridged := false
		for k := i + 1; k <= i+3 && k < len(lines); k++ {
			if numberedRe.MatchString(cleanLine(lines[k])) {
				end, i, bridged = k, k, true
				break
			}
		}
		if !bridged {
			break
		}
	}

	// Safety: a real prompt has a hint line within 3 rows below the
	// block or a ">" marker in it — a numbered markdown list in normal
	// agent output has neither.
	hasMarker := false
	for i := start; i <= end; i++ {
		if selectedRe.MatchString(cleanLine(lines[i])) || strings.HasPrefix(strings.TrimSpace(lines[i]), ">") {
			hasMarker = true
			break
		}
	}
	hintBelow := false
	for i := end + 1; i <= end+3 && i < len(lines); i++ {
		if isHint(cleanLine(lines[i])) {
			hintBelow = true
			break
		}
	}
	if !hasMarker && !hintBelow {
		return nil
	}

	q := &Question{Selected: -1}
	for i := start; i <= end; i++ {
		c := cleanLine(lines[i])
		if c == "" || isHint(c) {
			continue
		}
		if m := numberedRe.FindStringSubmatch(c); m != nil {
			q.Options = append(q.Options, Option{Num: atoi(m[1]), Label: m[2]})
			q.Numbered = true
		} else if m := selectedRe.FindStringSubmatch(c); m != nil {
			q.Options = append(q.Options, Option{Label: m[1]})
		} else if q.Numbered {
			continue // wrapped continuation of a long numbered label
		} else if m := indentedRe.FindStringSubmatch(lines[i]); m != nil {
			q.Options = append(q.Options, Option{Label: m[1]})
		} else {
			continue
		}
		if strings.HasPrefix(strings.TrimSpace(lines[i]), ">") {
			q.Selected = len(q.Options) - 1
		}
	}
	if len(q.Options) < 2 {
		return nil
	}
	if q.Selected < 0 && !q.Numbered {
		return nil
	}

	// Question text: nearest lines above the block; a line ending in
	// "?" anchors it.
	var txt []string
	blanks := 0
	for i := start - 1; i >= 0 && len(txt) < 3; i-- {
		c := cleanLine(lines[i])
		if c == "" {
			blanks++
			if blanks >= 2 && len(txt) > 0 {
				break
			}
			continue
		}
		blanks = 0
		if isHint(c) {
			continue
		}
		txt = append([]string{c}, txt...)
		if strings.HasSuffix(c, "?") {
			break
		}
	}
	q.Text = strings.Join(txt, " ")
	if q.Text == "" {
		q.Text = "(fråga utan text)"
	}

	h := sha256.New()
	h.Write([]byte(q.Text))
	for _, o := range q.Options {
		h.Write([]byte{0})
		h.Write([]byte(o.Label))
	}
	q.Hash = hex.EncodeToString(h.Sum(nil))[:16]
	return q
}

func atoi(s string) int {
	n := 0
	for _, r := range s {
		n = n*10 + int(r-'0')
	}
	return n
}