"use strict";

const express = require("express"),
  Promise = require("bluebird");

let photoDB;

require("../db/photos").then(function(db) {
  photoDB = db;
});

const MIN_DISTANCE_COMMIT = 0.0000001

const router = express.Router();

const upsertIdentity = async(id, {
    displayName,
    firstName,
    lastName,
    middleName
  }, res) => {

  if (displayName === undefined
    || firstName === undefined
    || lastName === undefined
    || middleName === undefined) {
    res.status(400).send({ message: `Missing fields` });
    return undefined;
  }

  const identity = {
    displayName,
    firstName,
    lastName,
    middleName,
    identityId: id
  };

  if (id === -1 || !id) {
    const [results, { lastId }] = await photoDB.sequelize.query(
      `INSERT INTO identities ` +
      '(displayName,firstName,lastName,middleName)' +
      'VALUES(:displayName,:firstName,:lastName,:middleName)', {
      replacements: identity
    });
    identity.identityId = lastId;
    console.log('Created identity: ', identity)
  } else {
   await photoDB.sequelize.query(
      `UPDATE identities ` +
      'SET ' +
      'displayName=:displayName, ' +
      'firstName=:firstName, ' +
      'lastName=:lastName, ' +
      'middleName=:middleName ' +
      'WHERE id=:identityId', {
      replacements: identity
    });
    console.log('Updated identity: ', identity)
  }

  return identity;
};


const populateRelatedFaces = async (identity, count) => {
  let limit = '';
  if (count) {
    limit = ` LIMIT ${count} `;
  }
  /* If this is a new identity, no faces are being requested --
   * just return the empty 'unknown face'. 
   * 
   * Otherwise, query the DB for 'count' faces */
  if (count !== undefined) {
    identity.relatedFaces = await photoDB.sequelize.query(
      "SELECT id AS faceId,photoId,faceConfidence " +
      "FROM faces " +
      "WHERE identityId=:identityId " +
      "ORDER BY distance ASC" +
      limit, {
        replacements: identity,
        type: photoDB.Sequelize.QueryTypes.SELECT,
        raw: true
    });
  } else {
    identity.relatedFaces = [];
  }

  /* If there are no faces, return the 'unknown face' */
  if (identity.relatedFaces.length === 0) {
    identity.relatedFaces.push({
      faceId: -1,
      photoId: -1,
      faceConfidence: 0
    });
  }

  identity.relatedFaces.forEach(face => {
    face.identityId = identity.identityId;
    face.distance = face.faceConfidence;
    face.descriptors = [];
    delete face.faceConfidence;
  });
}

/* Create new identity */
router.post('/', async (req, res) => {
  console.log(`POST ${req.url}`)
  if (!req.user.maintainer) {
    console.warn(`${req.user.name} attempted to modify photos.`);
    return res.status(401).send({ message: "Unauthorized to modify photos." });
  }

  const identity = await upsertIdentity(-1, req.body, res);
  if (!identity) {
    return;
  }
  updateIdentityFaces(identity);
  await populateRelatedFaces(identity, 1);
  return res.status(200).send(identity);
});

/* Update identity */
router.put('/:id', async (req, res) => {
  console.log(`PUT ${req.url}`)
  if (!req.user.maintainer) {
    console.warn(`${req.user.name} attempted to modify photos.`);
    return res.status(401).send({ message: "Unauthorized to modify photos." });
  }

  const { id } = req.params;
  if (!id || isNaN(+id)) {
    return res.status(400).send({ message: `Invalid identity id ${id}` });
  }

  const identity = await upsertIdentity(id, req.body, res);
  if (!identity) {
    return;
  }
  await updateIdentityFaces(identity);
  await populateRelatedFaces(identity);
  return res.status(200).send(identity);
});


router.delete('/:id', async (req, res) => {
  console.log(`DELETE ${req.url}`)
  if (!req.user.maintainer) {
    console.warn(`${req.user.name} attempted to modify photos.`);
    return res.status(401).send({ message: "Unauthorized to modify photos." });
  }

  const { id } = req.params;
  if (!id || isNaN(+id)) {
    return res.status(400).send({ message: `Invalid identity id ${id}` });
  }

  await photoDB.sequelize.query(
    'UPDATE faces SET distance=0,identityId=NULL ' +
    'WHERE identityId=:id', {
      replacements: { id }
    }
  );

  await photoDB.sequelize.query(
    'DELETE FROM identities ' +
    'WHERE id=:id', {
      replacements: { id }
  });

  return res.status(200).send({});
});

/* Given a faceId, find the closest defined identity and return
 * it as a guess -- does not modify the DB */
router.get("/faces/guess/:faceId", async (req, res) => {
  const faceId = parseInt(req.params.faceId);
  if (faceId != req.params.faceId) {
    return res.status(400).send({ message: "Invalid identity id." });
  }

  try {
    /* Look up the requested face... */
    const faces = await photoDB.sequelize.query(
      "SELECT faces.*,faceDescriptors.descriptors " +
      "FROM faces,faceDescriptors " +
      "WHERE faces.id=:faceId " +
      "AND faceDescriptors.id=faces.descriptorId", {
      replacements: { faceId },
      type: photoDB.Sequelize.QueryTypes.SELECT,
      raw: true
    });

    /* Look up all the identities... */
    const identities = await photoDB.sequelize.query(
      "SELECT * FROM identities", {
      type: photoDB.Sequelize.QueryTypes.SELECT,
      raw: true
    });
    identities.forEach(x => { x.identityId = x.id; delete x.id;});
    
    faces.forEach((face) => {
      const currentIdentityId = face.identityId;
      face.faceId = face.id;
      delete face.id;
      face.identity = null;


      identities.forEach((identity) => {
        if (!identity.descriptors 
        || currentIdentityId === identity.identityId) {
          return;
        }

        const distance = euclideanDistance(
          face.descriptors,
          identity.descriptors
        );

        if (face.identity === null) {
          face.identityId = identity.identityId;
          face.identity = identity;
          face.distance = distance;
          return;
        }

        if (distance < face.distance) {
          face.identityId = identity.identityId;
          face.identity = identity;
          face.distance = distance;
        }
      });
    });

    /* Delete the VGG-Face descriptors and add relatedFaces[0] */
    await Promise.map(faces, async (face) => {
      delete face.descriptors;
      if (face.identity.descriptors) {
        delete face.identity.descriptors;
      }
      if (!face.identity.relatedFaces) {
        await populateRelatedFaces(face.identity, 1);
      }
    }, {
      concurrency: 1
    });

    return res.status(200).json(faces);
  } catch (error) {
    console.error(error);
    return res.status(500).send("Error processing request.");
  };
});

router.put("/faces/remove/:id", async (req, res) => {
  console.log(`PUT ${req.url}`)
  if (!req.user.maintainer) {
    console.warn(`${req.user.name} attempted to modify photos.`);
    return res.status(401).send({ message: "Unauthorized to modify photos." });
  }

  const id = parseInt(req.params.id);
  if (id != req.params.id) {
    return res.status(400).send({ message: "Invalid identity id." });
  }

  if (!Array.isArray(req.body.faces) || req.body.faces.length == 0) {
    return res.status(400).send({ message: "No faces supplied." });
  }

  try {
    await photoDB.sequelize.query(
      "UPDATE faces SET identityId=null " +
      "WHERE id IN (:faceIds)", {
      replacements: {
        identityId: id,
        faceIds: req.body.faces
      }
    });
    const identity = {
      identityId: id,
      faces: req.body.faces
    };
    identity.faces = identity.faces.map(id => +id);

    /* Do not block on this call finishing -- update can occur
     * in the background */
    updateIdentityFaces(identity);

    return res.status(200).json(identity);
  } catch (error) {
    console.error(error);
    return res.status(500).send({message: "Error processing request." });
  };
});

router.put("/faces/add/:id", async (req, res) => {
  if (!req.user.maintainer) {
    console.warn(`${req.user.name} attempted to modify photos.`);
    return res.status(401).send("Unauthorized to modify photos.");
  }

  const id = parseInt(req.params.id);
  if (id != req.params.id) {
    return res.status(400).send("Invalid identity id.");
  }
  
  if (!Array.isArray(req.body.faces) || req.body.faces.length == 0) {
    return res.status(400).send("No faces supplied.");
  }

  try {
    await photoDB.sequelize.query(
      "UPDATE faces SET identityId=:identityId,classifiedBy='human' " +
      "WHERE id IN (:faceIds)", {
      replacements: {
        identityId: id,
        faceIds: req.body.faces
      }
    });
    const identity = {
      identityId: id,
      faces: req.body.faces
    };
    identity.faces = identity.faces.map(id => +id);

    /* Do not block on this call finishing -- update can occur
     * in the background */
    updateIdentityFaces(identity);
    return res.status(200).json(identity);
  } catch (error) {
    console.error(error);
    return res.status(500).send("Error processing request.");
  };
});


function bufferToFloat32Array(buffer) {
  return new Float64Array(buffer.buffer, 
    buffer.byteOffset, 
    buffer.byteLength / Float64Array.BYTES_PER_ELEMENT);
}

function euclideanDistanceArray(a, b) {
  let sum = 0;
  for (let i = 0; i < a.length; i++) {
    let delta = a[i] - b[i];
    sum += delta * delta;
  }
  return Math.sqrt(sum);
}

function euclideanDistance(a, b) {
  if (!a.buffer || !b.buffer) {
    return -1;
  }

  return euclideanDistanceArray(
    bufferToFloat32Array(a),
    bufferToFloat32Array(b)
  );
}

const getUnknownIdentity = async (faceCount) => {
  const unknownIdentity = {
    identityId: -1,
    lastName: '',
    firstName: '',
    middleName: '',
    displayName: 'Unknown',
    descriptors: new Float32Array(0),
    relatedFaces: [],
    facesCount: 0
  };
  const limit = faceCount 
  ? ` ORDER BY RANDOM() LIMIT ${faceCount} ` 
  : ' ORDER BY faceConfidence DESC ';
  unknownIdentity.relatedFaces = await photoDB.sequelize.query(
    "SELECT id AS faceId,photoId,faceConfidence " +
    "FROM faces WHERE identityId IS NULL AND classifiedBy != 'not-a-face' " +
    limit, {
    type: photoDB.Sequelize.QueryTypes.SELECT,
    raw: true
  });
  if (unknownIdentity.relatedFaces.length === 0) {
    unknownIdentity.relatedFaces.push({
      faceId: -1,
      photoId: -1,
      faceConfidence: 0
    });
  }
  unknownIdentity.relatedFaces.forEach(face => {
    face.identityId = -1;
    face.distance = face.faceConfidence;
    face.descriptors = new Float32Array(0);
    delete face.faceConfidence;
  });
  return unknownIdentity;
}

const round = (x, precision) => {
  if (precision === undefined) {
    precision = 2;
  }
  return Number.parseFloat(x).toFixed(precision);
};

/* Compute the identity's centroid descriptor from all faces
 * and determine closest face to that centroid. If either of
 * those values have changed, update the identity.
 * 
 * Also updates the 'distance' on each face to the identity
 * centroid.
 */
const updateIdentityFaces = async (identity) => {
  if (!identity.identityId) {
    throw Error(`identityId is not set.`);
  }

  if (!identity.descriptors) {
    const results = await photoDB.sequelize.query(
      "SELECT " +
      "descriptors,facesCount,faceId,displayName " +
      "FROM identities " +
      "WHERE id=:identityId", {
      replacements: identity,
      type: photoDB.Sequelize.QueryTypes.SELECT,
      raw: true
    });
    Object.assign(identity, results[0]);
    /* New identities do not have descriptors set */
  }

  if (identity.descriptors) {
    identity.descriptors = bufferToFloat32Array(identity.descriptors);
  }

  const faces = await photoDB.sequelize.query(
    "SELECT " +
    "faces.*,faceDescriptors.* " +
    "FROM faces,faceDescriptors " +
    "WHERE " +
    "faces.identityId=:identityId " +
    "AND faceDescriptors.id=faces.descriptorId", {
    replacements: identity,
    type: photoDB.Sequelize.QueryTypes.SELECT,
    raw: true
  });

  if (faces.length === 0) {
    return;
  }

  let average = undefined, 
    closestId = -1, 
    closestDistance = -1;
   
  /* First find the average centroid of all faces */
  faces.forEach((face) => {
    /* Convert the descriptors from buffer to array so they can be
     * modified */
    face.descriptors = bufferToFloat32Array(face.descriptors);

    /* First face starts the average sum */
    if (average === undefined) {
      average = face.descriptors.slice();
      return;
    }

    /* Add this face descriptor into the average descriptor */
    for (let i = 0; i < face.descriptors.length; i++) {
      average[i] = average[i] + face.descriptors[i];
    };
  });

  /* Divide sum of descriptors to create average centroid */
  for (let i = 0; i < average.length; i++) {
    average[i] = average[i] / faces.length;
  }

  /* Now compute the distance from each face to the new centroid */
  faces.forEach((face) => {
    let distance;

    distance = euclideanDistanceArray(
      face.descriptors,
      average
    );

    if (closestId === -1 || face.distance < closestDistance) {
      closestDistance = distance;
      closestId = face.id;
    }
  });

  /* Determine if the centroid for this identity has moved 
   * and for each relatedFace, update its distance to the centroid */
  if (!identity.descriptors) {
    console.log(`Identity ${identity.identityId} has no descriptors`);
  }
  let moved = (identity.descriptors === null ? 1 : 0)
    || Number
      .parseFloat(euclideanDistanceArray(identity.descriptors, average))
      .toFixed(4);
      
  const t = await photoDB.sequelize.transaction();
  try {
    /* If the average position has not changed, then face distances should
      * not change either! */
    await Promise.map(faces, async (face) => {
      /* All the buffer are already arrays, so use the short-cut version */
      const distance = Number
        .parseFloat(euclideanDistanceArray(face.descriptors, average))
        .toFixed(4);
  
      if (Math.abs(distance - face.distance) > MIN_DISTANCE_COMMIT) {
        console.log(
          `Updating face ${face.id} to ${round(distance, 2)} ` +
          `(${distance - face.distance}) ` +
          `from identity ${identity.identityId} (${identity.displayName})`);
        face.distance = distance;
        await photoDB.sequelize.query(
          'UPDATE faces SET distance=:distance WHERE id=:id', {
            replacements: face,
            transaction: t
          }
        );
      }
    }, {
      concurrency: 5
    });
 
    let sql = '';
    /* If there is a new closestId, then set the faceId field */
    if (closestId !== -1 && closestId !== identity.faceId) {
      console.log(
        `Updating identity ${identity.identityId} closest face to ${closestId}`);
      sql = `${sql} faceId=:faceId`;
      identity.faceId = closestId;
    }

    /* If the centroid changed, update the identity descriptors to
    * the new average */
    if (Math.abs(moved) > MIN_DISTANCE_COMMIT) {
      console.log(
        `Updating identity ${identity.identityId} centroid ` +
        `(moved ${Number.parseFloat(moved).toFixed(4)}).`);
      if (sql !== '') {
        sql = `${sql}, `;
      }
      sql = `${sql} descriptors=:descriptors`;
      // this: identity.descriptors = average;
      // gives: Invalid value Float64Array(2622)
      //
      // this: identity.descriptors = new Blob(average);
      // gives: Invalid value Blob { size: 54008, type: '' }
      //
      // this: identity.descriptors = Buffer.from(average);
      // gives: all zeroes
      //
      // this: identity.descriptors = Buffer.from(average.buffer);
      // gives: IT WORKS!!!
      identity.descriptors = Buffer.from(average.buffer);
    }

    /* If the number of faces changed, update the facesCount */
    if (identity.facesCount !== faces.length) {
      if (sql !== '') {
        sql = `${sql}, `;
      }
      console.log(
        `Updating identity ${identity.identityId} face count to ${faces.length}`);
      identity.facesCount = faces.length;
      sql = `${sql} facesCount=${faces.length}`;
    }

    /* If any of the above required changes, actually commit to the DB */
    if (sql !== '') {
      await photoDB.sequelize.query(
        `UPDATE identities SET ${sql} ` +
        `WHERE id=:identityId`, {
          replacements: identity,
          transaction: t
        }
      );
    }
    t.commit();
  } catch (error) {
    console.error(error);
    t.rollback();
    return;
  }
};

router.get("/:id?", async (req, res) => {
  console.log(`GET ${req.url}`);

  let id;

  if (req.params.id) {
    id = parseInt(req.params.id);
    if (id != req.params.id) {
      return res.status(400).send({ message: "Usage /[id]"});
    }
  }

  /* If identityId requested is -1, this is the "Unknown" identity
   * where all unmapped faces live. */
  if (id === -1) {
    const unknownIdentity = await getUnknownIdentity()
    return res.status(200).json([ unknownIdentity ]);
  }

  const filter = id ? "WHERE identities.id=:id " : "";

  const identities = await photoDB.sequelize.query(
    "SELECT " +
      "identities.id AS identityId," +
      "identities.firstName," +
      "identities.lastName," +
      "identities.middleName," +
      "identities.displayName," +
      "identities.faceId," +
      "identities.facesCount " +
    "FROM identities " +
    filter, {
    replacements: { id },
    type: photoDB.Sequelize.QueryTypes.SELECT,
    raw: true
  });

  await Promise.map(identities, async (identity) => {
    for (let field in identity) {
      if (field.match(/.*Name/) && identity[field] === null) {
        identity[field] = '';
      }
    }

    let where, limit = '';
    /* If id was not set, only return a single face */
    if (id === undefined) {
      if (identity.faceId !== -1 && identity.faceId !== null) {
        /* Return the identity faceId, and make sure the face
         * is associated with that id -- they can get out of sync
         * when faces are added/removed from an identity */
        where = 'faceId=:faceId AND identityId=:identityId';
      } else {
        where = 'identityId=:identityId';
        limit = 'LIMIT 1';
      }
    } else {
      where = 'identityId=:identityId'
    }

    identity.relatedFaces = await photoDB.sequelize.query(
      'SELECT id as faceId,identityId,photoId,distance ' +
      'FROM faces ' +
      `WHERE ${where} ` +
      'ORDER BY distance ASC ' +
      limit, {
        replacements: identity,
        type: photoDB.Sequelize.QueryTypes.SELECT,
        raw: true
      }
    );

    /* If this identity has at least one face associated with it,
     * and it does not yet have the 'closest' face assigned, update
     * the identity statistics.
     */
    if (identity.relatedFaces.length !== 0 
    && (!identity.faceId || identity.faceId === -1)) {
      await updateIdentityFaces(identity);
    }

    /* If there were no faces, then add a 'Unknown' face */
    if (identity.relatedFaces.length === 0) {
      identity.relatedFaces.push({
        faceId: -1,
        photoId: -1,
        identityId: identity.identityId,
        distance: 0,
        faceConfidence: 0
      });
    }
  }, {
    concurrency: 1 
  });

  /* If no ID was provided then this call is returning
   * a list of all identities -- we create a fake identity for all
   * unlabeled faces */
  if (!id) {
    const unknownIdentity = await getUnknownIdentity(1) 
    identities.push(unknownIdentity);
  }

  return res.status(200).json(identities);
});

module.exports = router;