package agent

import (
	"strings"
	"testing"
)

func TestSteerText(t *testing.T) {
	tests := []struct {
		name    string
		content string
		want    string
		wantOK  bool
	}{
		{
			name:    "happy path: prefix + newline + text",
			content: MidTurnSteerPrefix + "\nplease use smaller diffs",
			want:    "please use smaller diffs",
			wantOK:  true,
		},
		{
			name:    "prefix only, no user text",
			content: MidTurnSteerPrefix,
			want:    "",
			wantOK:  true,
		},
		{
			name:    "prefix with trailing whitespace only",
			content: MidTurnSteerPrefix + "\n  ",
			want:    "  ",
			wantOK:  true,
		},
		{
			name:    "round-trip through midTurnSteerMessage",
			content: midTurnSteerMessage("stop using such large diffs"),
			want:    "stop using such large diffs",
			wantOK:  true,
		},
		{
			name:    "user text with leading/trailing spaces preserved (matches live event)",
			content: MidTurnSteerPrefix + "\n   keep going but use read_file first   ",
			want:    "   keep going but use read_file first   ",
			wantOK:  true,
		},
		{
			name:    "regular user message, not steer",
			content: "please use smaller diffs",
			want:    "",
			wantOK:  false,
		},
		{
			name:    "empty string",
			content: "",
			want:    "",
			wantOK:  false,
		},
		{
			name:    "whitespace only",
			content: "   ",
			want:    "",
			wantOK:  false,
		},
		{
			name:    "prefix-like but truncated (no closing bracket)",
			content: "[Mid-turn steer queued by the user. Do not treat this as a new task\nplease go on",
			want:    "",
			wantOK:  false,
		},
		{
			name:    "prefix appears mid-message, not at start",
			content: "hey model " + MidTurnSteerPrefix + "\nuse smaller diffs",
			want:    "",
			wantOK:  false,
		},
		{
			name:    "multiline steer text preserved",
			content: MidTurnSteerPrefix + "\nline one\nline two",
			want:    "line one\nline two",
			wantOK:  true,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, ok := SteerText(tt.content)
			if ok != tt.wantOK {
				t.Errorf("SteerText() ok = %v, want %v", ok, tt.wantOK)
			}
			if got != tt.want {
				t.Errorf("SteerText() text = %q, want %q", got, tt.want)
			}
			// Sanity: when ok is true the result must never contain the prefix.
			if ok && strings.Contains(got, MidTurnSteerPrefix) {
				t.Errorf("SteerText() returned text still contains the prefix: %q", got)
			}
		})
	}
}

func TestMidTurnSteerMessageRoundTrip(t *testing.T) {
	inputs := []string{
		"stop",
		"use read_file instead of cat",
		"",
		"  keep going  ",
	}
	for _, in := range inputs {
		msg := midTurnSteerMessage(in)
		got, ok := SteerText(msg)
		if !ok {
			t.Errorf("SteerText(midTurnSteerMessage(%q)): not recognized as steer", in)
			continue
		}
		if got != in {
			t.Errorf("SteerText(midTurnSteerMessage(%q)) = %q, want %q", in, got, in)
		}
	}
}