// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later

// Package prompt recognizes fresh prompts and work-completion lines.
package prompt

import (
	"fmt"
	"regexp"
	"strings"

	"git.stormux.org/storm/fenrir/internal/screen"
)

var defaultPatterns = []*regexp.Regexp{
	regexp.MustCompile(`^(?:[$#>]|\[.*\]\s*[\\$#>]|[a-zA-Z0-9._-]+[\\$#>]|\S+@\S+.*[$#>])\s*$`),
	regexp.MustCompile(`(?i)\?\s*(?:\[(?:y/n|yes/no)\]|\((?:y/n|yes/no)\))\s*:?\s*$`),
	regexp.MustCompile(`(?i)^.*\bok\s*\[y/n\]\s*:?\s*$`),
	regexp.MustCompile(`(?i)^(?:\[sudo\]\s*password\s+for\s+.+|.*\bpassword|(?:please\s+)?enter\s+passphrase.*)\s*:\s*$`),
	regexp.MustCompile(`(?i)^(?:press\s+any\s+key\s+to\s+continue.*|are\s+you\s+sure\?.*|please\s+confirm.*)$`),
}

var completionPattern = regexp.MustCompile(`^Worked for (?:[0-9]+h(?: [0-9]+m)?(?: [0-9]+s)?|[0-9]+m(?: [0-9]+s)?|[0-9]+s)\s+•\s+(?:[1-9]|1[0-2]):[0-5][0-9]\s+(?:AM|PM)$`)

type Detector struct {
	exactMatches []string
	patterns     []*regexp.Regexp
	previous     map[string]int
	terminal     int
	generation   uint64
	rows, cols   int
	active       bool
}

func New(exactMatches, customPatterns []string) (*Detector, error) {
	detector := &Detector{exactMatches: append([]string(nil), exactMatches...)}
	for _, pattern := range customPatterns {
		compiled, err := regexp.Compile(pattern)
		if err != nil {
			return nil, fmt.Errorf("invalid prompt custom pattern %q: %w", pattern, err)
		}
		detector.patterns = append(detector.patterns, compiled)
	}
	return detector, nil
}

func (d *Detector) matches_prompt(text string) bool {
	if text == "" {
		return false
	}
	for _, exact := range d.exactMatches {
		if text == strings.TrimSpace(exact) {
			return true
		}
	}
	for _, patterns := range [][]*regexp.Regexp{d.patterns, defaultPatterns} {
		for _, pattern := range patterns {
			if pattern.MatchString(text) {
				return true
			}
		}
	}
	return false
}

// Observe runs even when speech is enabled, establishing a baseline before
// silence. Counts ignore row movement, so old prompts/completions scrolling
// through the screen cannot restore speech. Session/buffer/size changes only
// establish a new baseline; they never restore from another screen's history.
// Shell/interactive prompts must be on the cursor row. Completion lines can
// appear above an input area, as in a terminal coding assistant.
func (d *Detector) Observe(next screen.Snapshot) string {
	counts := make(map[string]int)
	for row := 0; row < next.Rows; row++ {
		counts[strings.TrimSpace(next.Text(row))]++
	}
	stable := d.previous != nil && d.active && next.Active && d.terminal == next.Terminal &&
		d.generation == next.Generation && d.rows == next.Rows && d.cols == next.Cols
	var result string
	if stable {
		for row := 0; row < next.Rows; row++ {
			text := strings.TrimSpace(next.Text(row))
			if counts[text] > d.previous[text] && (completionPattern.MatchString(text) || row == next.Y && d.matches_prompt(text)) {
				result = text
				break
			}
		}
	}
	d.previous = counts
	d.terminal, d.generation, d.rows, d.cols, d.active = next.Terminal, next.Generation, next.Rows, next.Cols, next.Active
	return result
}