const yaml = require('js-yaml');
const fs = require('fs-extra');
const path = require('node:path');
const crypto = require('node:crypto');
const { AgentAnalyzer } = require('./agent-analyzer');
const { ActivationBuilder } = require('./activation-builder');

/**
 * Converts agent YAML files to XML format with smart activation injection
 */
class YamlXmlBuilder {
  constructor() {
    this.analyzer = new AgentAnalyzer();
    this.activationBuilder = new ActivationBuilder();
  }

  /**
   * Deep merge two objects (for customize.yaml + agent.yaml)
   * @param {Object} target - Target object
   * @param {Object} source - Source object to merge in
   * @returns {Object} Merged object
   */
  deepMerge(target, source) {
    const output = { ...target };

    if (this.isObject(target) && this.isObject(source)) {
      for (const key of Object.keys(source)) {
        if (this.isObject(source[key])) {
          if (key in target) {
            output[key] = this.deepMerge(target[key], source[key]);
          } else {
            output[key] = source[key];
          }
        } else if (Array.isArray(source[key])) {
          // For arrays, append rather than replace (for commands)
          if (Array.isArray(target[key])) {
            output[key] = [...target[key], ...source[key]];
          } else {
            output[key] = source[key];
          }
        } else {
          output[key] = source[key];
        }
      }
    }

    return output;
  }

  /**
   * Check if value is an object
   */
  isObject(item) {
    return item && typeof item === 'object' && !Array.isArray(item);
  }

  /**
   * Load and merge agent YAML with customization
   * @param {string} agentYamlPath - Path to base agent YAML
   * @param {string} customizeYamlPath - Path to customize YAML (optional)
   * @returns {Object} Merged agent configuration
   */
  async loadAndMergeAgent(agentYamlPath, customizeYamlPath = null) {
    // Load base agent
    const agentContent = await fs.readFile(agentYamlPath, 'utf8');
    const agentYaml = yaml.load(agentContent);

    // Load customization if exists
    let merged = agentYaml;
    if (customizeYamlPath && (await fs.pathExists(customizeYamlPath))) {
      const customizeContent = await fs.readFile(customizeYamlPath, 'utf8');
      const customizeYaml = yaml.load(customizeContent);

      if (customizeYaml) {
        // Special handling: persona fields are merged, but only non-empty values override
        if (customizeYaml.persona) {
          const basePersona = merged.agent.persona || {};
          const customPersona = {};

          // Only copy non-empty customize values
          for (const [key, value] of Object.entries(customizeYaml.persona)) {
            if (value !== '' && value !== null && !(Array.isArray(value) && value.length === 0)) {
              customPersona[key] = value;
            }
          }

          // Merge non-empty customize values over base
          if (Object.keys(customPersona).length > 0) {
            merged.agent.persona = { ...basePersona, ...customPersona };
          }
        }

        // Merge metadata (only non-empty values)
        if (customizeYaml.agent && customizeYaml.agent.metadata) {
          const nonEmptyMetadata = {};
          for (const [key, value] of Object.entries(customizeYaml.agent.metadata)) {
            if (value !== '' && value !== null) {
              nonEmptyMetadata[key] = value;
            }
          }
          merged.agent.metadata = { ...merged.agent.metadata, ...nonEmptyMetadata };
        }

        // Append menu items (support both 'menu' and legacy 'commands')
        const customMenuItems = customizeYaml.menu || customizeYaml.commands;
        if (customMenuItems) {
          // Determine if base uses 'menu' or 'commands'
          if (merged.agent.menu) {
            merged.agent.menu = [...merged.agent.menu, ...customMenuItems];
          } else if (merged.agent.commands) {
            merged.agent.commands = [...merged.agent.commands, ...customMenuItems];
          } else {
            // Default to 'menu' for new agents
            merged.agent.menu = customMenuItems;
          }
        }

        // Append critical actions
        if (customizeYaml.critical_actions) {
          merged.agent.critical_actions = [...(merged.agent.critical_actions || []), ...customizeYaml.critical_actions];
        }
      }
    }

    return merged;
  }

  /**
   * Convert agent YAML to XML
   * @param {Object} agentYaml - Parsed agent YAML object
   * @param {Object} buildMetadata - Metadata about the build (file paths, hashes, etc.)
   * @returns {string} XML content
   */
  async convertToXml(agentYaml, buildMetadata = {}) {
    const agent = agentYaml.agent;
    const metadata = agent.metadata || {};

    // Analyze agent to determine needed handlers
    const profile = this.analyzer.analyzeAgentObject(agentYaml);

    // Build activation block only if not skipped
    let activationBlock = '';
    if (!buildMetadata.skipActivation) {
      activationBlock = await this.activationBuilder.buildActivation(
        profile,
        metadata,
        agent.critical_actions || [],
        buildMetadata.forWebBundle || false, // Pass web bundle flag
      );
    }

    // Start building XML
    let xml = '<!-- Powered by BMAD-CORE™ -->\n\n';
    xml += `# ${metadata.title || 'Agent'}\n\n`;

    xml += '```xml\n';

    // Agent opening tag
    const agentAttrs = [
      `id="${metadata.id || ''}"`,
      `name="${metadata.name || ''}"`,
      `title="${metadata.title || ''}"`,
      `icon="${metadata.icon || '🤖'}"`,
    ];

    // Add localskip attribute if present
    if (metadata.localskip === true) {
      agentAttrs.push('localskip="true"');
    }

    xml += `<agent ${agentAttrs.join(' ')}>\n`;

    // Activation block (only if not skipped)
    if (activationBlock) {
      xml += activationBlock + '\n';
    }

    // Persona section
    xml += this.buildPersonaXml(agent.persona);

    // Prompts section (if exists)
    if (agent.prompts) {
      xml += this.buildPromptsXml(agent.prompts);
    }

    // Menu section (support both 'menu' and legacy 'commands')
    const menuItems = agent.menu || agent.commands || [];
    xml += this.buildCommandsXml(menuItems);

    xml += '</agent>\n';
    xml += '```\n';

    return xml;
  }

  /**
   * Build metadata comment
   */
  buildMetadataComment(metadata) {
    const lines = ['<!-- BUILD-META', `  source: ${metadata.sourceFile || 'unknown'} (hash: ${metadata.sourceHash || 'unknown'})`];

    if (metadata.customizeFile) {
      lines.push(`  customize: ${metadata.customizeFile} (hash: ${metadata.customizeHash || 'unknown'})`);
    }

    lines.push(`  built: ${new Date().toISOString()}`, `  builder-version: ${metadata.builderVersion || '1.0.0'}`, '-->\n');

    return lines.join('\n');
  }

  /**
   * Build persona XML section
   */
  buildPersonaXml(persona) {
    if (!persona) return '';

    let xml = '  <persona>\n';

    if (persona.role) {
      xml += `    <role>${this.escapeXml(persona.role)}</role>\n`;
    }

    if (persona.identity) {
      xml += `    <identity>${this.escapeXml(persona.identity)}</identity>\n`;
    }

    if (persona.communication_style) {
      xml += `    <communication_style>${this.escapeXml(persona.communication_style)}</communication_style>\n`;
    }

    if (persona.principles) {
      // Principles can be array or string
      let principlesText;
      if (Array.isArray(persona.principles)) {
        principlesText = persona.principles.join(' ');
      } else {
        principlesText = persona.principles;
      }
      xml += `    <principles>${this.escapeXml(principlesText)}</principles>\n`;
    }

    xml += '  </persona>\n';

    return xml;
  }

  /**
   * Build prompts XML section
   */
  buildPromptsXml(prompts) {
    if (!prompts || prompts.length === 0) return '';

    let xml = '  <prompts>\n';

    for (const prompt of prompts) {
      xml += `    <prompt id="${prompt.id || ''}">\n`;
      xml += `      <![CDATA[\n`;
      xml += `      ${prompt.content || ''}\n`;
      xml += `      ]]>\n`;
      xml += `    </prompt>\n`;
    }

    xml += '  </prompts>\n';

    return xml;
  }

  /**
   * Build menu XML section (renamed from commands for clarity)
   * Auto-injects *help and *exit, adds * prefix to all triggers
   */
  buildCommandsXml(menuItems) {
    let xml = '  <menu>\n';

    // Always inject *help first
    xml += `    <item cmd="*help">Show numbered menu</item>\n`;

    // Add user-defined menu items with * prefix
    if (menuItems && menuItems.length > 0) {
      for (const item of menuItems) {
        // Build command attributes - add * prefix if not present
        let trigger = item.trigger || '';
        if (!trigger.startsWith('*')) {
          trigger = '*' + trigger;
        }

        const attrs = [`cmd="${trigger}"`];

        // Add handler attributes
        if (item.workflow) attrs.push(`workflow="${item.workflow}"`);
        if (item['validate-workflow']) attrs.push(`validate-workflow="${item['validate-workflow']}"`);
        if (item.exec) attrs.push(`exec="${item.exec}"`);
        if (item.tmpl) attrs.push(`tmpl="${item.tmpl}"`);
        if (item.data) attrs.push(`data="${item.data}"`);
        if (item.action) attrs.push(`action="${item.action}"`);

        xml += `    <item ${attrs.join(' ')}>${this.escapeXml(item.description || '')}</item>\n`;
      }
    }

    // Always inject *exit last
    xml += `    <item cmd="*exit">Exit with confirmation</item>\n`;

    xml += '  </menu>\n';

    return xml;
  }

  /**
   * Escape XML special characters
   */
  escapeXml(text) {
    if (!text) return '';
    return text
      .replaceAll('&', '&amp;')
      .replaceAll('<', '&lt;')
      .replaceAll('>', '&gt;')
      .replaceAll('"', '&quot;')
      .replaceAll("'", '&apos;');
  }

  /**
   * Calculate file hash for build tracking
   */
  async calculateFileHash(filePath) {
    if (!(await fs.pathExists(filePath))) {
      return null;
    }

    const content = await fs.readFile(filePath, 'utf8');
    return crypto.createHash('md5').update(content).digest('hex').slice(0, 8);
  }

  /**
   * Build agent XML from YAML files and return as string (for in-memory use)
   * @param {string} agentYamlPath - Path to agent YAML
   * @param {string} customizeYamlPath - Path to customize YAML (optional)
   * @param {Object} options - Build options
   * @returns {Promise<string>} XML content as string
   */
  async buildFromYaml(agentYamlPath, customizeYamlPath = null, options = {}) {
    // Load and merge YAML files
    const mergedAgent = await this.loadAndMergeAgent(agentYamlPath, customizeYamlPath);

    // Calculate hashes for build tracking
    const sourceHash = await this.calculateFileHash(agentYamlPath);
    const customizeHash = customizeYamlPath ? await this.calculateFileHash(customizeYamlPath) : null;

    // Build metadata
    const buildMetadata = {
      sourceFile: path.basename(agentYamlPath),
      sourceHash,
      customizeFile: customizeYamlPath ? path.basename(customizeYamlPath) : null,
      customizeHash,
      builderVersion: '1.0.0',
      includeMetadata: options.includeMetadata !== false,
      skipActivation: options.skipActivation === true,
      forWebBundle: options.forWebBundle === true,
    };

    // Convert to XML and return
    return await this.convertToXml(mergedAgent, buildMetadata);
  }

  /**
   * Build agent XML from YAML files
   * @param {string} agentYamlPath - Path to agent YAML
   * @param {string} customizeYamlPath - Path to customize YAML (optional)
   * @param {string} outputPath - Path to write XML file
   * @param {Object} options - Build options
   */
  async buildAgent(agentYamlPath, customizeYamlPath, outputPath, options = {}) {
    // Use buildFromYaml to get XML content
    const xml = await this.buildFromYaml(agentYamlPath, customizeYamlPath, options);

    // Write output file
    await fs.ensureDir(path.dirname(outputPath));
    await fs.writeFile(outputPath, xml, 'utf8');

    // Calculate hashes for return value
    const sourceHash = await this.calculateFileHash(agentYamlPath);
    const customizeHash = customizeYamlPath ? await this.calculateFileHash(customizeYamlPath) : null;

    return {
      success: true,
      outputPath,
      sourceHash,
      customizeHash,
    };
  }
}

module.exports = { YamlXmlBuilder };