/**
 * Markdown renderer for interview profiles.
 * Converts collected answers into markdown output based on profile configuration.
 */

import type { InterviewProfile, InterviewStep, CaptureTextStep, CaptureTextLineStep, CaptureFrontmatterStep, LoopStep } from "./types";

export interface RenderAnswers {
  collectedData: Map<string, unknown>;
  loopContexts: Map<string, unknown[]>;
}

/**
 * Render profile answers to markdown string.
 * Deterministic and testable.
 */
export function renderProfileToMarkdown(
  profile: InterviewProfile,
  answers: RenderAnswers
): string {
  const output: string[] = [];
  
  for (const step of profile.steps) {
    const stepOutput = renderStep(step, answers);
    if (stepOutput) {
      output.push(stepOutput);
    }
  }
  
  return output.join("\n\n").trim();
}

/**
 * Render a single step to markdown.
 */
function renderStep(step: InterviewStep, answers: RenderAnswers): string | null {
  switch (step.type) {
    case "capture_text":
      return renderCaptureText(step, answers);
    case "capture_text_line":
      return renderCaptureTextLine(step, answers);
    case "capture_frontmatter":
      // Frontmatter is handled separately, skip here
      return null;
    case "loop":
      return renderLoop(step, answers);
    case "instruction":
    case "llm_dialog":
    case "review":
      // These don't produce markdown output
      return null;
    default:
      return null;
  }
}

/**
 * Render capture_text step.
 */
function renderCaptureText(step: CaptureTextStep, answers: RenderAnswers): string | null {
  const value = answers.collectedData.get(step.key);
  if (!value || String(value).trim() === "") {
    return null;
  }
  
  const text = String(value);
  
  // Use template if provided
  if (step.output?.template) {
    return renderTemplate(step.output.template, {
      text,
      field: step.key,
      value: text,
    });
  }
  
  // Default: use section if provided, otherwise just the text
  if (step.section) {
    return `${step.section}\n\n${text}`;
  }
  
  return text;
}

/**
 * Render capture_text_line step.
 */
function renderCaptureTextLine(step: CaptureTextLineStep, answers: RenderAnswers): string | null {
  const value = answers.collectedData.get(step.key);
  if (!value || String(value).trim() === "") {
    return null;
  }
  
  const text = String(value);
  
  // Use template if provided
  if (step.output?.template) {
    return renderTemplate(step.output.template, {
      text,
      field: step.key,
      value: text,
    });
  }
  
  // Default: just the text
  return text;
}

/**
 * Render capture_frontmatter step.
 * Note: This is typically handled separately, but included for completeness.
 */
function renderCaptureFrontmatter(step: CaptureFrontmatterStep, answers: RenderAnswers): string | null {
  const value = answers.collectedData.get(step.key);
  if (value === undefined || value === null || String(value).trim() === "") {
    return null;
  }
  
  // Use template if provided
  if (step.output?.template) {
    return renderTemplate(step.output.template, {
      text: String(value),
      field: step.field,
      value: String(value),
    });
  }
  
  // Default: no markdown output (frontmatter is handled separately)
  return null;
}

/**
 * Render loop step (recursive, supports arbitrary nesting depth).
 */
function renderLoop(step: LoopStep, answers: RenderAnswers): string | null {
  return renderLoopRecursive(step, answers, 0);
}

/**
 * Recursive helper to render loop items with nested steps.
 * Supports arbitrary nesting depth (no hard limit, but practical limits apply due to stack size).
 */
function renderLoopRecursive(step: LoopStep, answers: RenderAnswers, depth: number): string | null {
  // Safety check: prevent infinite recursion (practical limit: 100 levels)
  if (depth > 100) {
    console.warn(`Loop nesting depth ${depth} exceeds practical limit, stopping recursion`);
    return null;
  }
  
  const items = answers.loopContexts.get(step.key);
  if (!items || items.length === 0) {
    return null;
  }
  
  const itemOutputs: string[] = [];
  
  for (const item of items) {
    if (!item || typeof item !== "object") {
      continue;
    }
    
    const itemParts: string[] = [];
    
    // Render each nested step for this item (recursively)
    for (const nestedStep of step.items) {
      const fieldValue = (item as Record<string, unknown>)[nestedStep.key];
      
      if (nestedStep.type === "capture_text") {
        if (fieldValue && String(fieldValue).trim()) {
          const text = String(fieldValue);
          const captureStep = nestedStep as CaptureTextStep;
          
          // Use template if provided
          if (captureStep.output?.template) {
            itemParts.push(renderTemplate(captureStep.output.template, {
              text,
              field: nestedStep.key,
              value: text,
            }));
          } else {
            // Default: just the text
            itemParts.push(text);
          }
        }
      } else if (nestedStep.type === "capture_text_line") {
        if (fieldValue && String(fieldValue).trim()) {
          const text = String(fieldValue);
          const captureStep = nestedStep as CaptureTextLineStep;
          
          // Use template if provided
          if (captureStep.output?.template) {
            itemParts.push(renderTemplate(captureStep.output.template, {
              text,
              field: nestedStep.key,
              value: text,
            }));
          } else {
            // Default: just the text
            itemParts.push(text);
          }
        }
      } else if (nestedStep.type === "capture_frontmatter") {
        if (fieldValue && String(fieldValue).trim()) {
          const captureStep = nestedStep as CaptureFrontmatterStep;
          
          // Use template if provided
          if (captureStep.output?.template) {
            itemParts.push(renderTemplate(captureStep.output.template, {
              text: String(fieldValue),
              field: captureStep.field,
              value: String(fieldValue),
            }));
          }
        }
      } else if (nestedStep.type === "loop") {
        // Recursively handle nested loop: fieldValue should be an array of items
        if (Array.isArray(fieldValue) && fieldValue.length > 0) {
          const nestedLoopStep = nestedStep as LoopStep;
          
          // Create a temporary answers object for the nested loop
          // The nested loop items are stored in fieldValue, so we need to create
          // a temporary loopContexts map for the nested loop
          const nestedAnswers: RenderAnswers = {
            collectedData: answers.collectedData,
            loopContexts: new Map(answers.loopContexts),
          };
          nestedAnswers.loopContexts.set(nestedLoopStep.key, fieldValue);
          
          // Recursively render the nested loop
          const nestedOutput = renderLoopRecursive(nestedLoopStep, nestedAnswers, depth + 1);
          if (nestedOutput) {
            itemParts.push(nestedOutput);
          }
        }
      }
    }
    
    if (itemParts.length > 0) {
      itemOutputs.push(itemParts.join("\n\n"));
    }
  }
  
  if (itemOutputs.length === 0) {
    return null;
  }
  
  // Check if first nested step has a section header (for backwards compatibility)
  const firstNestedStep = step.items[0];
  let sectionHeader: string | null = null;
  if (firstNestedStep && firstNestedStep.type === "capture_text" && firstNestedStep.section) {
    sectionHeader = firstNestedStep.section;
  }
  
  // Join items with configured separator or default newline
  const joinStr = step.output?.join || "\n\n";
  const loopContent = itemOutputs.join(joinStr);
  
  // Prepend section header if available
  if (sectionHeader) {
    return `${sectionHeader}\n\n${loopContent}`;
  }
  
  return loopContent;
}

/**
 * Render template string with token replacement.
 * Tokens: {text}, {field}, {value}
 */
function renderTemplate(template: string, tokens: { text: string; field: string; value: string }): string {
  return template
    .replace(/\{text\}/g, tokens.text)
    .replace(/\{field\}/g, tokens.field)
    .replace(/\{value\}/g, tokens.value);
}