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

package reader

import (
	"slices"
	"strings"
	"time"
	"unicode"

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

func (r *Reader) Configure_indentation(mode string) { r.indentationMode = mode }

func (r *Reader) indentation_feedback(announce bool) *presentation.Message {
	level, valid := r.review.Indentation()
	if !valid {
		return nil // Blank rows preserve the last meaningful level.
	}
	changed := r.indentKnown && level != r.lastIndent
	r.lastIndent, r.indentKnown = level, true
	if !announce || !changed || r.indentationMode == "" || r.indentationMode == "none" {
		return nil
	}
	message := presentation.Indentation_message(level, r.indentationMode)
	return &message
}

func (r *Reader) automatic_indentation(previous, next screen.Snapshot, switched bool) *presentation.Message {
	if switched {
		r.indentKnown = false
	}
	// Passive program output must not create indentation chatter. Match Python's
	// cursor-input window and suppress automatic cursor feedback during review.
	announce := !switched && next.Active && r.automatic && r.cursorEcho && r.trackingMode == "cursor" && !r.review.Active() &&
		r.region_state().allows(next.X, next.Y, next.Cols, true, true) &&
		!r.applicationInputAt.IsZero() && time.Since(r.applicationInputAt) < 300*time.Millisecond
	if announce {
		// A hidden leading-whitespace edit must not produce indentation cues
		// at an otherwise visible cursor farther along the same row.
		for col, char := range next.Line(next.Y) {
			if !r.region_state().allows(col, next.Y, next.Cols, true, true) {
				announce = false
				break
			}
			if !unicode.IsSpace(char) {
				break
			}
		}
	}
	if announce && previous.Y == next.Y {
		// Horizontal input only reports a genuine leading-whitespace edit, not
		// movement within a line or ordinary typing/deletion in its content.
		before, after := previous.Text(previous.Y), next.Text(next.Y)
		announce = strings.TrimSpace(before) == strings.TrimSpace(after) && before != after
	} else if announce {
		// A cursor moving with new program output is not line navigation.
		announce = slices.Equal(previous.Line(next.Y), next.Line(next.Y))
	}
	return r.indentation_feedback(announce)
}