import type { Schema, ReverseReferenceSchema } from "../types.js";
import { parseSchema } from "../parser.js";

export interface ReverseReferenceDeclaration {
  fieldName: string;
  tableName: string;
  foreignKey: string;
  isOptional: boolean;
  schema: ReverseReferenceSchema;
}

export interface TypeDeclaration {
  name: string;
  schema: Schema;
}

/**
 * Parse a type declaration from a comment line.
 * Format: # type TypeName = schema
 * Returns null if the line is not a type declaration.
 */
export function parseTypeDeclaration(
  line: string,
  commentChar: string = "#",
): { typeName: string; schemaString: string } | null {
  const trimmed = line.trim();
  // Must start with the comment character
  if (!trimmed.startsWith(commentChar)) return null;

  const content = trimmed.slice(commentChar.length).trim();

  // Match pattern: type TypeName = schema
  const match = content.match(/^type\s+([A-Z][a-zA-Z0-9]*)\s*=\s*(.+)$/);
  if (!match) return null;

  const [, typeName, schemaString] = match;
  return { typeName, schemaString };
}

/**
 * Expand a type name to its schema by replacing the type name with its schema inline.
 * Returns the schema string with type names expanded, or null if not a type name.
 */
function expandTypeName(
  schemaString: string,
  declaredTypes: Map<string, string>,
): string | null {
  const trimmed = schemaString.trim();
  if (declaredTypes.has(trimmed)) {
    return declaredTypes.get(trimmed)!;
  }
  return null;
}

/**
 * Recursively expand all type name references in a schema string.
 * Handles unions, tuples, arrays, and nested structures.
 */
export function expandSchemaString(
  schemaString: string,
  declaredTypes: Map<string, string>,
): string {
  let result = schemaString;

  // Keep expanding until no more changes (handles recursive dependencies)
  let prev = "";
  while (prev !== result) {
    prev = result;
    result = expandSchemaInString(result, declaredTypes);
  }

  return result;
}

/**
 * Single pass of type name expansion in a schema string.
 */
function expandSchemaInString(
  schemaString: string,
  declaredTypes: Map<string, string>,
): string {
  // Check if the entire string is a type name
  const expanded = expandTypeName(schemaString.trim(), declaredTypes);
  if (expanded !== null) {
    return expanded;
  }

  // Handle union types (recursively expand each member)
  if (schemaString.includes("|")) {
    // Split by | but respect quotes
    const parts = splitByToken(schemaString, "|");
    if (parts.length > 1) {
      const expandedParts = parts.map((part) =>
        expandSchemaInString(part.trim(), declaredTypes),
      );
      return expandedParts.join(" | ");
    }
  }

  // Handle tuple/array syntax [el1; el2; ...] or [elements]
  // Check if it's a bracketed structure
  if (schemaString.startsWith("[") && schemaString.endsWith("]")) {
    const inner = schemaString.slice(1, -1);
    // Check if it's semicolon-separated (tuple syntax)
    if (inner.includes(";")) {
      const elements = splitByToken(inner, ";");
      const expandedElements = elements.map((el) =>
        expandSchemaInString(el.trim(), declaredTypes),
      );
      return `[${expandedElements.join("; ")}]`;
    }
    // Otherwise it's a simple array, expand recursively
    return `[${expandSchemaInString(inner, declaredTypes)}]`;
  }

  // Check if it's a type name reference (only uppercase start to avoid conflicts with primitives)
  const typeNameMatch = schemaString.trim().match(/^[A-Z][a-zA-Z0-9]*$/);
  if (typeNameMatch) {
    const expanded = expandTypeName(schemaString.trim(), declaredTypes);
    if (expanded !== null) {
      return expanded;
    }
  }

  return schemaString;
}

/**
 * Split a string by a token, respecting quoted strings.
 */
function splitByToken(str: string, token: string): string[] {
  const result: string[] = [];
  let current = "";
  let inQuote: string | null = null;

  for (let i = 0; i < str.length; i++) {
    const char = str[i];

    if (inQuote) {
      if (char === inQuote && str[i - 1] !== "\\") {
        inQuote = null;
      }
      current += char;
    } else if (char === '"' || char === "'") {
      inQuote = char;
      current += char;
    } else if (char === token && inQuote === null) {
      result.push(current);
      current = "";
    } else {
      current += char;
    }
  }

  if (current.length > 0 || str.endsWith(token)) {
    result.push(current);
  }

  return result;
}

/**
 * Resolve type name references within a schema using declared types.
 * For example, if "Trigger" is a declared type, references to "Trigger" in
 * other schemas will be replaced with the actual Trigger schema definition.
 */
export function resolveTypeReferences(
  schema: Schema,
  declaredTypes: Map<string, Schema>,
): Schema {
  switch (schema.type) {
    case "union":
      return {
        type: "union",
        members: schema.members.map((m) =>
          resolveTypeReferences(m, declaredTypes),
        ),
      };
    case "tuple":
      return {
        type: "tuple",
        elements: schema.elements.map((el) => ({
          name: el.name,
          schema: resolveTypeReferences(el.schema, declaredTypes),
        })),
      };
    case "array":
      return {
        type: "array",
        element: resolveTypeReferences(schema.element, declaredTypes),
      };
    case "reference":
      // Don't resolve references to other tables
      return schema;
    default:
      return schema;
  }
}

/**
 * Resolve type name references in a type declaration's schema string.
 * Called after all type names are known.
 */
export function resolveTypeDeclarationSchema(
  schemaString: string,
  declaredTypes: Map<string, Schema>,
): Schema {
  const schema = parseSchema(schemaString.trim());
  return resolveTypeReferences(schema, declaredTypes);
}

/**
 * Parse a reverse reference declaration from a comment line.
 * Format: # inject fieldName = ~tableName(foreignKey)
 * Returns null if the line is not a reverse reference declaration.
 */
export function parseReverseReferenceDeclaration(
  line: string,
  commentChar: string = "#",
): ReverseReferenceDeclaration | null {
  const trimmed = line.trim();
  // Must start with the comment character
  if (!trimmed.startsWith(commentChar)) return null;

  const content = trimmed.slice(commentChar.length).trim();

  // Match pattern: inject fieldName = ~tableName(foreignKey)
  const match = content.match(/^inject\s+(\w+)\s*=\s*~(\w+)\((\w+)\)(\?)?$/);
  if (!match) return null;

  const [, fieldName, tableName, foreignKey, optionalMark] = match;
  const isOptional = optionalMark === "?";

  const schema: ReverseReferenceSchema = {
    type: "reverseReference",
    tableName,
    foreignKey,
    isOptional,
  };

  return {
    fieldName,
    tableName,
    foreignKey,
    isOptional,
    schema,
  };
}