// Package evidence is the activity port: a dumb active-window sensor behind a
// Source interface, plus the value types it emits. It makes no judgment about
// whether a window is on-task — that is the advisor's job in a later milestone.
package evidence

import (
	"context"
	"regexp"
	"strings"
	"unicode"
)

// EvidenceHealth records whether the sensor could observe the active window.
type EvidenceHealth struct {
	Available bool   // true when a window was observed
	Reason    string // empty when Available; populated when not
}

// WindowSnapshot is one observation of the active window.
type WindowSnapshot struct {
	Title  string // full _NET_WM_NAME (raw; used in live view + raw log)
	Class  string // WM_CLASS
	Health EvidenceHealth
}

// Source is the activity port. Watch runs until ctx is cancelled, invoking
// onChange on every active-window change, and once immediately with the
// current window.
type Source interface {
	Watch(ctx context.Context, onChange func(WindowSnapshot))
}

// titleNoise matches the legacy clock/ratio/percent runs that pollute bucket
// keys (e.g. "1:23", "50.5%", "-3.0"). Ported verbatim from the Rust impl.
var titleNoise = regexp.MustCompile(`-?\d+([:.]\d+)+%?`)

// extraSpace collapses the whitespace runs left behind by the scrubs below.
var extraSpace = regexp.MustCompile(`\s+`)

// ScrubTitle normalizes a window title into a stable bucket key. It drops
// volatile numeric runs (clocks, ratios, percentages) and any non-ASCII symbol
// or control rune. The latter covers the animated spinner frames terminal apps
// (e.g. Claude Code) cycle through their title — braille and dingbat glyphs are
// both Unicode symbol category, so a single task no longer fragments into dozens
// of buckets. Letters and digits of every script survive, as do ASCII symbols
// (so "C++" is not mangled). Leftover whitespace is collapsed. The raw event log
// keeps the unscrubbed title; only bucket keys (and their display) are scrubbed.
func ScrubTitle(title string) string {
	title = titleNoise.ReplaceAllString(title, "")
	title = strings.Map(func(r rune) rune {
		if unicode.IsControl(r) || (r > unicode.MaxASCII && unicode.IsSymbol(r)) {
			return -1
		}
		return r
	}, title)
	return strings.TrimSpace(extraSpace.ReplaceAllString(title, " "))
}