import { underscore } from '@angular-devkit/core/src/utils/strings';
import { Rule, SchematicContext, Tree } from '@angular-devkit/schematics';
import { Model, ModelRelation, ClassRelationEnum } from '@vmfvmf/ywtc-lib';
import { error } from 'console';
import { getPrjSrd } from '../../router.gen';


let fileName = 'create-relations-fks.sql';

export function gen(model: Model): Rule {
  return (tree: Tree, _context: SchematicContext) => { 

    const createRelationsFksSqlPath = `ywtc-output/${getPrjSrd().prjNDashd}-backend/sql/${fileName}`;
    const updatedCreateRelationsFksSql = updateCreateRelationsFksSql(getFileContent(tree, createRelationsFksSqlPath)!, model);
    tree.overwrite(createRelationsFksSqlPath, updatedCreateRelationsFksSql);
    
    return tree;
  
  };
}
  
  function getFileContent(tree: Tree, fileName: string) {
    if (!tree.exists(fileName)) {
      throw new Error(`File: ${fileName} NOT FOUND.`)
    }
  
    return tree.read(fileName)?.toString();
  }
  
  // fks are created on child side ever.
  function updateCreateRelationsFksSql(content: string, model: Model) {
    const jtcAdd = '/*JTCADD*/';
    if (content.includes(jtcAdd)) {
      let txt = getFks(model);
      if (txt) {
        content = content.replace(jtcAdd, `${txt}\n\n${jtcAdd}`);
      }
    } else {
      throw error(`The ${fileName} file is missing ${jtcAdd}!!!`);
    }
    return content;
  }

function getFks(model: Model) {
  return model.relations
    .filter((rel: ModelRelation) => ([ClassRelationEnum.ManyToOne].includes(rel.relation)))
    .map((rel: ModelRelation) => getFk(underscore(model.name), underscore(rel.toModelName)))
    .join('\n\n') + 
    model.relations
    .filter((rel: ModelRelation) => ([ClassRelationEnum.OneToOne].includes(rel.relation)))
    .map((rel: ModelRelation) => getFk(underscore(model.name), underscore(rel.toModelName)))
    .join('\n\n');
}

function getFk(tableWithFk: string, otherTable: string) {
    return `ALTER TABLE ${getPrjSrd().dbName}.${tableWithFk} ADD
\tCONSTRAINT \`fk_${tableWithFk}_${otherTable}\`
\tFOREIGN KEY (\`${otherTable}_id\`)
\tREFERENCES \`${getPrjSrd().dbName}\`.\`${otherTable}\` (\`id\`)
\tON DELETE CASCADE
\tON UPDATE RESTRICT;`;
  }