package agent

import (
    "bytes"
    "strings"
    "testing"
    "time"
)

// Verify HeadlessOutput satisfies the Output interface at compile time.
var _ Output = (*HeadlessOutput)(nil)

func TestHeadlessOutput_StreamText(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    out.StreamText("hello ")
    out.StreamText("world")

    if got := stdout.String(); got != "hello world" {
        t.Errorf("StreamText: stdout = %q, want %q", got, "hello world")
    }
    if stderr.Len() != 0 {
        t.Errorf("StreamText: unexpected stderr output: %q", stderr.String())
    }
}

func TestHeadlessOutput_StreamDone(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    out.StreamText("response")
    out.StreamDone(100, 50)

    if got := stdout.String(); got != "response\n" {
        t.Errorf("StreamDone: stdout = %q, want %q", got, "response\n")
    }
    if stderr.Len() != 0 {
        t.Errorf("StreamDone: unexpected stderr output: %q", stderr.String())
    }
}

func TestHeadlessOutput_ToolCallStart(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    out.ToolCallStart("read_file", map[string]any{"path": "/tmp/test.go"})

    if stdout.Len() != 0 {
        t.Errorf("ToolCallStart: unexpected stdout output: %q", stdout.String())
    }
    got := stderr.String()
    if !strings.Contains(got, "read_file") {
        t.Errorf("ToolCallStart: stderr = %q, missing tool name", got)
    }
    if !strings.HasPrefix(got, "→ ") {
        t.Errorf("ToolCallStart: stderr = %q, missing arrow prefix", got)
    }
}

func TestHeadlessOutput_ToolCallResult(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    out.ToolCallResult("read_file", "file contents here", false, 150*time.Millisecond)

    if stdout.Len() != 0 {
        t.Errorf("ToolCallResult: unexpected stdout output: %q", stdout.String())
    }
    got := stderr.String()
    if !strings.Contains(got, "read_file") {
        t.Errorf("ToolCallResult: stderr = %q, missing tool name", got)
    }
    if !strings.Contains(got, "ok") {
        t.Errorf("ToolCallResult: stderr = %q, missing ok status", got)
    }
    if !strings.Contains(got, "file contents here") {
        t.Errorf("ToolCallResult: stderr = %q, missing result content", got)
    }
}

func TestHeadlessOutput_ToolCallResult_Error(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    out.ToolCallResult("write_file", "permission denied", true, 50*time.Millisecond)

    got := stderr.String()
    if !strings.Contains(got, "ERROR") {
        t.Errorf("ToolCallResult error: stderr = %q, missing ERROR status", got)
    }
}

func TestHeadlessOutput_ToolCallResult_LongResult(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    longResult := strings.Repeat("x", 300)
    out.ToolCallResult("search", longResult, false, 100*time.Millisecond)

    got := stderr.String()
    if strings.Contains(got, strings.Repeat("x", 300)) {
        t.Error("ToolCallResult: long result should be truncated")
    }
    if !strings.Contains(got, "...") {
        t.Error("ToolCallResult: truncated result should end with ...")
    }
}

func TestHeadlessOutput_SystemMessage(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    out.SystemMessage("compacting conversation")

    if stdout.Len() != 0 {
        t.Errorf("SystemMessage: unexpected stdout output: %q", stdout.String())
    }
    got := stderr.String()
    if !strings.Contains(got, "[system]") {
        t.Errorf("SystemMessage: stderr = %q, missing [system] prefix", got)
    }
    if !strings.Contains(got, "compacting conversation") {
        t.Errorf("SystemMessage: stderr = %q, missing message", got)
    }
}

func TestHeadlessOutput_Error(t *testing.T) {
    var stdout, stderr bytes.Buffer
    out := newHeadlessOutput(&stdout, &stderr)

    out.Error("something went wrong")

    if stdout.Len() != 0 {
        t.Errorf("Error: unexpected stdout output: %q", stdout.String())
    }
    got := stderr.String()
    if !strings.Contains(got, "[error]") {
        t.Errorf("Error: stderr = %q, missing [error] prefix", got)
    }
    if !strings.Contains(got, "something went wrong") {
        t.Errorf("Error: stderr = %q, missing message", got)
    }
}

func TestNewHeadlessOutput(t *testing.T) {
    out := NewHeadlessOutput()
    if out == nil {
        t.Fatal("NewHeadlessOutput returned nil")
    }
    if out.stdout == nil || out.stderr == nil {
        t.Error("NewHeadlessOutput: writers should not be nil")
    }
}