<?php

namespace Tests\Unit;

use App\Exceptions\PromptRenderException;
use App\Services\PromptRenderer;
use PHPUnit\Framework\TestCase;

class PromptRendererTest extends TestCase
{
    private PromptRenderer $renderer;

    protected function setUp(): void
    {
        parent::setUp();

        $this->renderer = new PromptRenderer();
    }

    public function test_extract_variables_returns_empty_list_without_variables(): void
    {
        $this->assertSame([], $this->renderer->extractVariables(''));
        $this->assertSame([], $this->renderer->extractVariables('Plain text, no placeholders at all.'));
    }

    public function test_extract_variables_returns_unique_names_in_first_occurrence_order(): void
    {
        $body = 'Hello {{name}}, here is {{content}}. Again: {{name}} and {{extra}}.';

        $this->assertSame(['name', 'content', 'extra'], $this->renderer->extractVariables($body));
    }

    public function test_extract_variables_tolerates_inner_whitespace(): void
    {
        $this->assertSame(
            ['content'],
            $this->renderer->extractVariables('{{content}} {{  content  }}')
        );
        $this->assertSame(
            ['a_b', 'A-B'],
            $this->renderer->extractVariables('{{a_b}} and {{ A-B }}')
        );

        // `$` is not in the variable charset, so this stays literal.
        $this->assertSame([], $this->renderer->extractVariables('{{$a_b}}'));
    }

    public function test_invalid_tokens_are_not_treated_as_variables(): void
    {
        $body = '{{}} and {{a b}} and {{a!b}} and {{ }} stay literal';

        $this->assertSame([], $this->renderer->extractVariables($body));
    }

    public function test_render_replaces_every_occurrence(): void
    {
        $rendered = $this->renderer->render(
            'Hi {{name}}! Send {{name}} the file.',
            ['name' => 'Ada']
        );

        $this->assertSame('Hi Ada! Send Ada the file.', $rendered);
    }

    public function test_render_returns_body_unchanged_without_variables(): void
    {
        $body = 'Nothing to do here.';

        $this->assertSame($body, $this->renderer->render($body, ['ignored' => 'x']));
    }

    public function test_render_is_strict_about_missing_variables(): void
    {
        try {
            $this->renderer->render('A: {{alpha}} B: {{beta}} C: {{gamma}}', ['beta' => 'b']);
            $this->fail('Expected PromptRenderException was not thrown.');
        } catch (PromptRenderException $exception) {
            $this->assertSame(['alpha', 'gamma'], $exception->missingVariables);
            $this->assertSame('Missing variables: alpha, gamma', $exception->getMessage());
        }
    }

    public function test_render_treats_non_string_values_as_missing(): void
    {
        try {
            $this->renderer->render('Count: {{count}}', ['count' => 42]);
            $this->fail('Expected PromptRenderException was not thrown.');
        } catch (PromptRenderException $exception) {
            $this->assertSame(['count'], $exception->missingVariables);
        }

        try {
            $this->renderer->render('Count: {{count}}', ['count' => null]);
            $this->fail('Expected PromptRenderException was not thrown.');
        } catch (PromptRenderException $exception) {
            $this->assertSame(['count'], $exception->missingVariables);
        }
    }

    public function test_render_accepts_empty_string_values(): void
    {
        $this->assertSame(
            'Title: ',
            $this->renderer->render('Title: {{title}}', ['title' => ''])
        );
    }

    public function test_render_ignores_extra_values(): void
    {
        $rendered = $this->renderer->render(
            'Only {{used}}',
            ['used' => 'yes', 'extra' => 'no']
        );

        $this->assertSame('Only yes', $rendered);
    }

    public function test_inserted_values_are_not_re_scanned_for_variables(): void
    {
        $rendered = $this->renderer->render(
            'Hello {{name}}, and {{other}}.',
            ['name' => '{{other}}', 'other' => 'world']
        );

        $this->assertSame('Hello {{other}}, and world.', $rendered);
    }

    public function test_missing_variables_are_reported_in_template_order(): void
    {
        try {
            $this->renderer->render('{{zulu}} {{alpha}} {{zulu}}', []);
            $this->fail('Expected PromptRenderException was not thrown.');
        } catch (PromptRenderException $exception) {
            $this->assertSame(['zulu', 'alpha'], $exception->missingVariables);
        }
    }
}