mcp-vala/examples/chat-server.vala

/*
 * Chat MCP Server Example
 *
 * This example demonstrates how to create an MCP server that provides
 * chat-related prompts for different conversation scenarios. It shows how to
 * implement and register multiple prompt templates.
 *
 * Compile with:
 * valac --pkg mcp-vala --pkg json-glib-1.0 --pkg gee-0.8 --pkg posix chat-server.vala -o chat-server
 */

using Mcp;
using Posix;

/**
 * Chat server that provides conversation prompts.
 */
public class ChatServer : GLib.Object {
    private Mcp.Core.Server server;
    
    /**
     * Creates a new ChatServer.
     */
    public ChatServer () {
        // Create server information
        var server_info = new Mcp.Types.Protocol.ServerInfo (
            "chat-server",
            "1.0.0"
        );
        server_info.description = "MCP server providing chat and conversation prompts";
        
        // Create server capabilities with prompts enabled
        var capabilities = new Mcp.Types.Protocol.ServerCapabilities ();
        capabilities.logging = true;
        capabilities.prompts = new Mcp.Types.Protocol.PromptsCapabilities ();
        
        // Create server
        server = new Mcp.Core.Server (server_info, capabilities);
        
        // Register chat prompt templates
        setup_prompts ();
    }
    
    /**
     * Sets up chat prompt templates.
     */
    private void setup_prompts () {
        // Register conversation starter prompt
        var conversation_starter = new ConversationStarterPrompt ();
        try {
            server.prompt_manager.register_template ("conversation_starter", conversation_starter);
        } catch (Error e) {
            GLib.stderr.printf ("Failed to register conversation starter prompt: %s\n", e.message);
        }
        
        // Register code review prompt
        var code_review = new CodeReviewPrompt ();
        try {
            server.prompt_manager.register_template ("code_review", code_review);
        } catch (Error e) {
            GLib.stderr.printf ("Failed to register code review prompt: %s\n", e.message);
        }
        
        // Register brainstorming prompt
        var brainstorming = new BrainstormingPrompt ();
        try {
            server.prompt_manager.register_template ("brainstorming", brainstorming);
        } catch (Error e) {
            GLib.stderr.printf ("Failed to register brainstorming prompt: %s\n", e.message);
        }
        
        // Register interview prompt
        var interview = new InterviewPrompt ();
        try {
            server.prompt_manager.register_template ("interview", interview);
        } catch (Error e) {
            GLib.stderr.printf ("Failed to register interview prompt: %s\n", e.message);
        }
        
        // Register story writing prompt
        var story_writing = new StoryWritingPrompt ();
        try {
            server.prompt_manager.register_template ("story_writing", story_writing);
        } catch (Error e) {
            GLib.stderr.printf ("Failed to register story writing prompt: %s\n", e.message);
        }
    }
    
    /**
     * Runs the server.
     *
     * @return Exit code
     */
    public async int run () {
        try {
            // Start the server
            bool started = yield server.start ();
            if (!started) {
                GLib.stderr.printf ("Failed to start server\n");
                return 1;
            }
            
            // Chat server started successfully
            // Available prompts: conversation_starter, code_review, brainstorming, interview, story_writing
            // Waiting for MCP client connections...
            
            // Run the main loop
            var main_loop = new MainLoop ();
            
            // Connect shutdown signal
            server.shutdown.connect (() => {
                main_loop.quit ();
            });
            
            main_loop.run ();
            
            return 0;
        } catch (Error e) {
            GLib.stderr.printf ("Server error: %s\n", e.message);
            return 1;
        }
    }
}

/**
 * Conversation starter prompt template.
 */
public class ConversationStarterPrompt : Mcp.Prompts.BaseTemplate {
    /**
     * Creates a new ConversationStarterPrompt.
     */
    public ConversationStarterPrompt () {
        base ("conversation_starter", "Conversation Starter", "Generates conversation starter prompts for different contexts");
        
        // Add arguments
        add_argument ("context", "Context", "The context or situation for the conversation (e.g., professional, casual, networking)", true);
        add_argument ("topic", "Topic", "The main topic to discuss", false);
        add_argument ("tone", "Tone", "The tone of the conversation (formal, casual, friendly, enthusiastic)", false);
        add_argument ("participants", "Participants", "Number of participants expected", false);
    }
    
    /**
     * {@inheritDoc}
     */
    protected override Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> generate_messages (GLib.Variant arguments) {
        var messages = new Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> ();
        
        string context = get_string_arg_variant (arguments, "context");
        string? topic = get_string_arg_variant (arguments, "topic", null);
        string? tone = get_string_arg_variant (arguments, "tone", null);
        int? participants = get_int_arg_variant (arguments, "participants", 2);
        
        string template = """Generate a conversation starter for a {{context}} context{{#topic}} focused on {{topic}}{{/topic}}{{#tone}} with a {{tone}} tone{{/tone}}{{#participants}} for {{participants}} participants{{/participants}}.

The conversation starter should:
1. Be appropriate for the specified context
2. Engage participants naturally
3. Set a positive and collaborative atmosphere
4. Lead to meaningful discussion
5. Be concise but inviting

Please provide 3-5 different conversation starter options, each with a brief explanation of when it would be most effective.""";
        
        messages.add (create_user_message (template, arguments));
        return messages;
    }
    
    /**
     * Gets a string argument from the arguments object.
     */
    private string? get_string_arg_variant (GLib.Variant arguments, string name, string? default_value = null) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("s")).get_string ();
        }
        return default_value;
    }
    
    /**
     * Gets an integer argument from the arguments object.
     */
    private int get_int_arg_variant (GLib.Variant arguments, string name, int default_value = 0) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("i")).get_int32 ();
        }
        return default_value;
    }
}

/**
 * Code review prompt template.
 */
public class CodeReviewPrompt : Mcp.Prompts.BaseTemplate {
    /**
     * Creates a new CodeReviewPrompt.
     */
    public CodeReviewPrompt () {
        base ("code_review", "Code Review", "Generates a comprehensive code review prompt");
        
        // Add arguments
        add_argument ("code", "Code", "The code to review", true);
        add_argument ("language", "Language", "Programming language of the code", true);
        add_argument ("focus", "Focus Area", "Specific areas to focus on (security, performance, readability, best_practices, all)", false);
        add_argument ("experience_level", "Experience Level", "Target experience level (beginner, intermediate, advanced)", false);
        add_argument ("file_type", "File Type", "Type of file (function, class, module, script, config)", false);
    }
    
    /**
     * {@inheritDoc}
     */
    protected override Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> generate_messages (GLib.Variant arguments) {
        var messages = new Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> ();
        
        string code = get_string_arg_variant (arguments, "code");
        string language = get_string_arg_variant (arguments, "language");
        string? focus = get_string_arg_variant (arguments, "focus", "all");
        string? experience_level = get_string_arg_variant (arguments, "experience_level", "intermediate");
        string? file_type = get_string_arg_variant (arguments, "file_type", "code");
        
        string template = """Please perform a comprehensive code review of the following {{language}} {{file_type}}:

```{{language}}
{{code}}
```

Review Focus: {{focus}}
Target Audience: {{experience_level}} developers

Please analyze the code and provide feedback on:

1. **Code Quality & Readability**
   - Clarity and maintainability
   - Naming conventions
   - Code organization and structure
   - Comments and documentation

2. **Functionality & Logic**
   - Correctness of implementation
   - Edge cases handled
   - Algorithm efficiency
   - Logic flow and control structures

3. **Best Practices & Standards**
   - Language-specific conventions
   - Design patterns usage
   - Error handling
   - Security considerations

4. **Performance & Optimization**
   - Time and space complexity
   - Resource usage
   - Potential bottlenecks
   - Optimization opportunities

5. **Testing & Maintainability**
   - Testability of the code
   - Modularity and reusability
   - Coupling and cohesion
   - Future extensibility

{{#focus}}
For the {{focus}} focus, please pay special attention to:
- Security vulnerabilities and potential exploits
- Performance bottlenecks and optimization opportunities
- Code readability and maintainability issues
- Adherence to established best practices
{{/focus}}

Please provide:
- Specific line-by-line feedback where relevant
- Overall assessment and summary
- Concrete suggestions for improvement
- Positive aspects worth noting
- Priority levels for issues found (critical, high, medium, low)

Format your response constructively with clear explanations and actionable recommendations.""";
        
        messages.add (create_user_message (template, arguments));
        return messages;
    }
    
    /**
     * Gets a string argument from the arguments object.
     */
    private string? get_string_arg_variant (GLib.Variant arguments, string name, string? default_value = null) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("s")).get_string ();
        }
        return default_value;
    }
}

/**
 * Brainstorming prompt template.
 */
public class BrainstormingPrompt : Mcp.Prompts.BaseTemplate {
    /**
     * Creates a new BrainstormingPrompt.
     */
    public BrainstormingPrompt () {
        base ("brainstorming", "Brainstorming", "Generates structured brainstorming prompts");
        
        // Add arguments
        add_argument ("topic", "Topic", "The main topic or problem to brainstorm", true);
        add_argument ("brainstorm_type", "Type", "Type of brainstorming (ideas, solutions, pros_cons, mind_map)", false);
        add_argument ("constraints", "Constraints", "Any constraints or limitations to consider", false);
        add_argument ("time_limit", "Time Limit", "Time limit for brainstorming session in minutes", false);
        add_argument ("participants", "Participants", "Number of participants", false);
    }
    
    /**
     * {@inheritDoc}
     */
    protected override Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> generate_messages (GLib.Variant arguments) {
        var messages = new Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> ();
        
        string topic = get_string_arg_variant (arguments, "topic");
        string? brainstorm_type = get_string_arg_variant (arguments, "brainstorm_type", "ideas");
        string? constraints = get_string_arg_variant (arguments, "constraints", null);
        int? time_limit = get_int_arg_variant (arguments, "time_limit", 30);
        int? participants = get_int_arg_variant (arguments, "participants", 1);
        
        string template = """Facilitate a {{brainstorm_type}} brainstorming session for the following topic:

**Topic:** {{topic}}

{{#constraints}}
**Constraints/Limitations:** {{constraints}}
{{/constraints}}

**Session Details:**
- Duration: {{time_limit}} minutes
- Participants: {{participants}}
- Type: {{brainstorm_type}} brainstorming

Please structure the session as follows:

1. **Warm-up (2-3 minutes)**
   - Briefly restate the topic and objectives
   - Set positive, creative atmosphere
   - Establish basic ground rules

2. **Divergent Thinking Phase** ({{time_limit_minus_5}} minutes)
   - Generate as many {{#ideas}}ideas{{/ideas}}{{#solutions}}potential solutions{{/solutions}}{{#pros_cons}}pros and cons{{/pros_cons}} as possible
   - Encourage wild and creative thinking
   - No judgment or criticism during this phase
   - Build on others' ideas when applicable

3. **Convergent Thinking Phase** (5 minutes)
   - Group similar {{#ideas}}ideas{{/ideas}}{{#solutions}}solutions{{/solutions}}{{#pros_cons}}points{{/pros_cons}}
   - Evaluate and prioritize
   - Look for patterns and connections
   - Select most promising options

4. **Action Planning (2-3 minutes)**
   - Identify next steps
   - Assign responsibilities if applicable
   - Set follow-up timeline

{{#ideas}}
Focus on quantity over quality initially. Use techniques like:
- Word association
- Mind mapping
- SCAMPER (Substitute, Combine, Adapt, Modify, Put to other uses, Eliminate, Reverse)
- Random word stimulation
{{/ideas}}

{{#solutions}}
Focus on practical and innovative approaches:
- Break the problem into smaller parts
- Consider analogies from different domains
- Think about first principles
- Challenge assumptions
{{/solutions}}

{{#pros_cons}}
Create balanced columns for advantages and disadvantages:
- Consider short-term and long-term effects
- Think about different stakeholders
- Evaluate feasibility and resources needed
{{/pros_cons}}

Please provide specific facilitation techniques and keep the energy high throughout the session!""";
        
        // Add computed value for time limit
        var builder = new VariantBuilder (new VariantType ("a{sv}"));
        
        // Copy all existing arguments
        var iter = arguments.iterator ();
        string key;
        Variant value;
        while (iter.next ("{sv}", out key, out value)) {
            builder.add ("{sv}", key, value);
        }
        
        // Add computed value
        builder.add ("{sv}", "time_limit_minus_5", new Variant.int32 (time_limit - 5));
        
        var modified_args = builder.end ();
        
        messages.add (create_user_message (template, modified_args));
        return messages;
    }
    
    /**
     * Gets a string argument from the arguments object.
     */
    private string? get_string_arg_variant (GLib.Variant arguments, string name, string? default_value = null) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("s")).get_string ();
        }
        return default_value;
    }
    
    /**
     * Gets an integer argument from the arguments object.
     */
    private int get_int_arg_variant (GLib.Variant arguments, string name, int default_value = 0) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("i")).get_int32 ();
        }
        return default_value;
    }
}

/**
 * Interview prompt template.
 */
public class InterviewPrompt : Mcp.Prompts.BaseTemplate {
    /**
     * Creates a new InterviewPrompt.
     */
    public InterviewPrompt () {
        base ("interview", "Interview", "Generates interview questions for different contexts");
        
        // Add arguments
        add_argument ("role", "Role", "Position being interviewed for", true);
        add_argument ("interview_type", "Type", "Type of interview (technical, behavioral, case_study, situational)", false);
        add_argument ("experience_level", "Experience Level", "Target experience level (junior, mid, senior, lead)", false);
        add_argument ("duration", "Duration", "Interview duration in minutes", false);
        add_argument ("company", "Company", "Company or organization name", false);
    }
    
    /**
     * {@inheritDoc}
     */
    protected override Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> generate_messages (GLib.Variant arguments) {
        var messages = new Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> ();
        
        string role = get_string_arg_variant (arguments, "role");
        string? interview_type = get_string_arg_variant (arguments, "interview_type", "technical");
        string? experience_level = get_string_arg_variant (arguments, "experience_level", "mid");
        int? duration = get_int_arg_variant (arguments, "duration", 60);
        string? company = get_string_arg_variant (arguments, "company", null);
        
        string template = """Generate a comprehensive interview plan for a {{experience_level}} {{role}} position at {{#company}}{{company}}{{/company}}{{^company}}the company{{/company}}.

**Interview Details:**
- Type: {{interview_type}} interview
- Duration: {{duration}} minutes
- Experience Level: {{experience_level}}

Please create an interview structure that includes:

1. **Introduction & Ice Breakers** (5 minutes)
   - Welcome and introduction
   - Brief company/role overview
   - Comfort-building questions

2. **Experience & Background** (10-15 minutes)
   - Previous relevant experience
   - Technical skills and competencies
   - Project highlights and achievements
   - Career motivation and goals

3. **{{#technical}}Technical Assessment{{/technical}}{{#behavioral}}Behavioral Questions{{/behavioral}}{{#case_study}}Case Study{{/case_study}}{{#situational}}Situational Questions{{/situational}}** (20-30 minutes)

{{#technical}}
- Technical skills assessment
- Problem-solving scenarios
- Code review or system design
- Technology stack questions
- Best practices and patterns
{{/technical}}

{{#behavioral}}
- Teamwork and collaboration examples
- Conflict resolution
- Leadership and initiative
- Time management and prioritization
- Dealing with failure or setbacks
{{/behavioral}}

{{#case_study}}
- Real-world problem scenarios
- Analytical thinking assessment
- Decision-making process
- Strategic thinking
- Business impact consideration
{{/case_study}}

{{#situational}}
- "What would you do if..." scenarios
- Priority handling
- Ethical dilemmas
- Customer/client situations
- Pressure and deadline situations
{{/situational}}

4. **Candidate Questions** (10-15 minutes)
   - Questions about the role, team, and company
   - Growth and development opportunities
   - Company culture and values
   - Next steps and timeline

5. **Closing** (5 minutes)
   - Summary and next steps
   - Final questions from candidate
   - Clear communication of follow-up process

For each section, provide:
- Specific questions to ask
- What to look for in answers
- Red flags to watch for
- Evaluation criteria

Tailor the difficulty and depth of questions appropriately for a {{experience_level}} level candidate.""";
        
        // Add conditional values
        var builder = new VariantBuilder (new VariantType ("a{sv}"));
        
        // Copy all existing arguments
        var iter = arguments.iterator ();
        string key;
        Variant value;
        while (iter.next ("{sv}", out key, out value)) {
            builder.add ("{sv}", key, value);
        }
        
        // Add conditional values
        builder.add ("{sv}", "technical", new Variant.boolean (interview_type == "technical"));
        builder.add ("{sv}", "behavioral", new Variant.boolean (interview_type == "behavioral"));
        builder.add ("{sv}", "case_study", new Variant.boolean (interview_type == "case_study"));
        builder.add ("{sv}", "situational", new Variant.boolean (interview_type == "situational"));
        
        var modified_args = builder.end ();
        
        messages.add (create_user_message (template, modified_args));
        return messages;
    }
    
    /**
     * Gets a string argument from the arguments object.
     */
    private string? get_string_arg_variant (GLib.Variant arguments, string name, string? default_value = null) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("s")).get_string ();
        }
        return default_value;
    }
    
    /**
     * Gets an integer argument from the arguments object.
     */
    private int get_int_arg_variant (GLib.Variant arguments, string name, int default_value = 0) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("i")).get_int32 ();
        }
        return default_value;
    }
}

/**
 * Story writing prompt template.
 */
public class StoryWritingPrompt : Mcp.Prompts.BaseTemplate {
    /**
     * Creates a new StoryWritingPrompt.
     */
    public StoryWritingPrompt () {
        base ("story_writing", "Story Writing", "Generates creative writing prompts and story structure guidance");
        
        // Add arguments
        add_argument ("genre", "Genre", "Story genre (fantasy, scifi, mystery, romance, thriller, horror, literary)", false);
        add_argument ("theme", "Theme", "Central theme or message", false);
        add_argument ("setting", "Setting", "Time and place of the story", false);
        add_argument ("characters", "Characters", "Brief character descriptions", false);
        add_argument ("plot_point", "Plot Point", "Starting plot point or inciting incident", false);
        add_argument ("story_length", "Story Length", "Target length (flash, short, novella, novel)", false);
        add_argument ("audience", "Audience", "Target audience (children, ya, adult)", false);
    }
    
    /**
     * {@inheritDoc}
     */
    protected override Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> generate_messages (GLib.Variant arguments) {
        var messages = new Gee.ArrayList<Mcp.Prompts.Types.PromptMessage> ();
        
        string? genre = get_string_arg_variant (arguments, "genre", "general");
        string? theme = get_string_arg_variant (arguments, "theme", null);
        string? setting = get_string_arg_variant (arguments, "setting", null);
        string? characters = get_string_arg_variant (arguments, "characters", null);
        string? plot_point = get_string_arg_variant (arguments, "plot_point", null);
        string? story_length = get_string_arg_variant (arguments, "story_length", "short");
        string? audience = get_string_arg_variant (arguments, "audience", "adult");
        
        string template = """Generate a comprehensive story writing guide for a {{genre}} story.

**Story Parameters:**
{{#theme}}Theme: {{theme}}{{/theme}}
{{#setting}}Setting: {{setting}}{{/setting}}
{{#characters}}Characters: {{characters}}{{/characters}}
{{#plot_point}}Plot Point: {{plot_point}}{{/plot_point}}
Target Length: {{story_length}}
Target Audience: {{audience}}

Please provide a structured story guide that includes:

1. **Story Structure Outline**
   - Three-act structure or hero's journey framework
   - Key plot points and turning points
   - Character arcs and development
   - Pacing recommendations for {{story_length}} fiction

2. **{{genre}} Genre Conventions**
   - Tropes and expectations for {{genre}} stories
   - How to innovate within the genre
   - Reader satisfaction elements
   - Common pitfalls to avoid

3. **Character Development Guidance**
{{#characters}}
   - How to develop the specified characters
   - Character voice and dialogue tips
   - Relationship dynamics
{{/characters}}
{{^characters}}
   - Creating compelling original characters
   - Protagonist and antagonist development
   - Supporting cast considerations
{{/characters}}

4. **World-Building Elements**
{{#setting}}
   - How to bring the setting to life
   - Sensory details and atmosphere
   - Integrating setting with plot
{{/setting}}
{{^setting}}
   - Creating immersive original worlds
   - Balancing description with action
   - Consistency considerations
{{/setting}}

5. **Writing Style & Voice**
   - Narrative perspective recommendations
   - Tense and POV consistency
   - Dialogue vs. narration balance
   - Pacing for {{story_length}} fiction

6. **{{theme}}Theme Integration**
   - Weaving {{theme}} naturally into the narrative
   - Symbolism and metaphor opportunities
   - Avoiding heavy-handed messaging
   - Subtle thematic reinforcement

7. **Target Audience Considerations**
   - Age-appropriate content and complexity
   - Themes and topics suitable for {{audience}} readers
   - Reading level and vocabulary
   - Cultural sensitivity and inclusivity

8. **Writing Process & Tips**
   - Daily word count goals
   - Overcoming writer's block
   - Revision and editing strategies
   - Getting feedback and improving

Please provide specific, actionable advice that will help the writer create a compelling {{genre}} story that resonates with {{audience}} readers.""";
        
        // Add conditional values
        var builder = new VariantBuilder (new VariantType ("a{sv}"));
        
        // Copy all existing arguments
        var iter = arguments.iterator ();
        string key;
        Variant value;
        while (iter.next ("{sv}", out key, out value)) {
            builder.add ("{sv}", key, value);
        }
        
        var modified_args = builder.end ();
        
        messages.add (create_user_message (template, modified_args));
        return messages;
    }
    
    /**
     * Gets a string argument from the arguments object.
     */
    private string? get_string_arg_variant (GLib.Variant arguments, string name, string? default_value = null) {
        if (arguments.lookup_value (name, null) != null) {
            return arguments.lookup_value (name, new VariantType ("s")).get_string ();
        }
        return default_value;
    }
}

/**
 * Main function.
 *
 * @param args Command line arguments
 * @return Exit code
 */
public static int main (string[] args) {
    // Create and run the server
    var server = new ChatServer ();
    
    // Handle Ctrl+C to gracefully shutdown
    // For now, we'll skip signal handling to get the build working
    
    var loop = new MainLoop ();
    
    // Run the server
    server.run.begin ((obj, res) => {
        loop.quit ();
    });
    
    // Keep the main loop running
    loop.run ();
    
    return 0;
}