const CouchDB = require("../../db")
const newid = require("../../db/newid")

exports.fetch = async function(ctx) {
  const db = new CouchDB(ctx.user.instanceId)
  const body = await db.query("database/by_type", {
    include_docs: true,
    key: ["model"],
  })

  ctx.body = body.rows.map(row => row.doc)
}

exports.find = async function(ctx) {
  const db = new CouchDB(ctx.user.instanceId)
  const model = await db.get(ctx.params.id)
  ctx.body = model
}

exports.save = async function(ctx) {
  const db = new CouchDB(ctx.user.instanceId)
  const { recordImport, ...rest } = ctx.request.body
  const modelToSave = {
    type: "model",
    _id: newid(),
    views: {},
    ...rest,
  }

  // rename record fields when table column is renamed
  const { _rename } = modelToSave
  if (_rename) {
    const records = await db.query(`database/all_${modelToSave._id}`, {
      include_docs: true,
    })
    const docs = records.rows.map(({ doc }) => {
      doc[_rename.updated] = doc[_rename.old]
      delete doc[_rename.old]
      return doc
    })

    await db.bulkDocs(docs)
    delete modelToSave._rename
  }

  // update schema of non-statistics views when new columns are added
  for (let view in modelToSave.views) {
    const modelView = modelToSave.views[view]
    if (!modelView) continue

    if (modelView.schema.group || modelView.schema.field) continue
    modelView.schema = modelToSave.schema
  }

  const result = await db.post(modelToSave)
  modelToSave._rev = result.rev

  const { schema } = ctx.request.body
  for (let key in schema) {
    // model has a linked record
    if (schema[key].type === "link") {
      // create the link field in the other model
      const linkedModel = await db.get(schema[key].modelId)
      linkedModel.schema[modelToSave.name] = {
        name: modelToSave.name,
        type: "link",
        modelId: modelToSave._id,
        constraints: {
          type: "array",
        },
      }
      await db.put(linkedModel)
    }
  }

  const designDoc = await db.get("_design/database")
  designDoc.views = {
    ...designDoc.views,
    [`all_${modelToSave._id}`]: {
      map: `function(doc) {
        if (doc.modelId === "${modelToSave._id}") {
          emit(doc._id); 
        }
      }`,
    },
  }
  await db.put(designDoc)

  if (recordImport && recordImport.path) {
    // Populate the table with records imported from CSV in a bulk update
    const csv = require("csvtojson")
    const json = await csv().fromFile(recordImport.path)
    const records = json.map(record => ({
      ...record,
      modelId: modelToSave._id,
    }))
    await db.bulkDocs(records)
  }

  ctx.status = 200
  ctx.message = `Model ${ctx.request.body.name} saved successfully.`
  ctx.body = modelToSave
}

exports.destroy = async function(ctx) {
  const db = new CouchDB(ctx.user.instanceId)

  const modelToDelete = await db.get(ctx.params.modelId)

  await db.remove(modelToDelete)

  const modelViewId = `all_${ctx.params.modelId}`

  // Delete all records for that model
  const records = await db.query(`database/${modelViewId}`)
  await db.bulkDocs(
    records.rows.map(record => ({ _id: record.id, _deleted: true }))
  )

  // Delete linked record fields in dependent models
  for (let key in modelToDelete.schema) {
    const { type, modelId } = modelToDelete.schema[key]
    if (type === "link") {
      const linkedModel = await db.get(modelId)
      delete linkedModel.schema[modelToDelete.name]
      await db.put(linkedModel)
    }
  }

  // delete the "all" view
  const designDoc = await db.get("_design/database")
  delete designDoc.views[modelViewId]
  await db.put(designDoc)

  ctx.status = 200
  ctx.message = `Model ${ctx.params.modelId} deleted.`
}