<!--
 This file is part of the Meeds project (https://meeds.io/).
 
 Copyright (C) 2020 - 2021 Meeds Association contact@meeds.io
 
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 3 of the License, or (at your option) any later version.
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 Lesser General Public License for more details.
 
 You should have received a copy of the GNU Lesser General Public License
 along with this program; if not, write to the Free Software Foundation,
 Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
-->
<template>
  <v-card
    width="340"
    height="350"
    class="d-flex flex-column"
    outlined>
    <v-card-title class="d-flex flex-column justify-center pb-2">
      <v-icon>mdi-cash-multiple</v-icon>
      <span>{{ $t('buyOrSell') }}</span>
    </v-card-title>
    <v-card-text class="d-flex flex-column flex-grow-1 pt-2">
      <v-text-field
        v-model="fromValue"
        :loading="loadingAmount"
        :rules="fromValueValidator"
        :hide-details="isFromValueValid"
        class="align-center"
        placeholder="0.0"
        large
        outlined
        dense>
        <template #append>
          <v-chip
            outlined
            x-small
            class="mt-1 me-1"
            @click="setMaxValue">
            {{ $t('max') }}
          </v-chip>
          <div class="mt-1">
            {{ buy && 'ETH' || 'MEED' }}
          </div>
        </template>
      </v-text-field>
      <v-btn
        icon
        class="mx-auto my-2"
        @click="switchInputs"
        x-large>
        <v-icon size="48">mdi-autorenew</v-icon>
      </v-btn>
      <v-text-field
        v-model="toValueDisplay"
        placeholder="0.0"
        class="align-center"
        hide-details
        large
        outlined
        dense
        disabled
        filled>
        <template #append>
          <div class="mt-1">
            {{ buy && 'MEED' || 'ETH' }}
          </div>
        </template>
      </v-text-field>
      <v-card-actions>
        <div class="d-flex flex-column mx-auto mt-4">
          <div v-if="swapInToSteps || !hasSufficientAllowedTokens" class="mx-auto">({{ $t('step') }} {{ step }} / 2)</div>
          <v-btn
            v-if="hasSufficientAllowedTokens"
            :loading="!!sendingTransaction"
            :disabled="disabledButton"
            class="ma-auto"
            @click="sendSwapTransaction">
            <span class="text-capitalize">
              {{ swapButtonLabel }}
            </span>
          </v-btn>
          <v-btn
            v-else
            :loading="!!sendingTransaction"
            :disabled="disabledButton"
            class="ma-auto"
            @click="sendApproveTransaction">
            <span class="text-capitalize">
              {{ approveButtonLabel }}
            </span>
          </v-btn>
        </div>
      </v-card-actions>
    </v-card-text>
  </v-card>
</template>
<script>
export default {
  data: () => ({
    slippage: 0.05,
    deadlineMinutes: 30,
    computingAmount: false,
    swapInToSteps: false,
    sendingTransaction: 0,
    step: 1,
    buy: true,
    fromValue: null,
    toValue: null,
    startSearchAfterInMilliseconds: 600,
    endTypingKeywordTimeout: 50,
    startTypingKeywordTimeout: 0,
    typing: false,
  }),
  computed: Vuex.mapState({
    address: state => state.address,
    language: state => state.language,
    tradeGasLimit: state => state.tradeGasLimit,
    approvalGasLimit: state => state.approvalGasLimit,
    sushiswapRouterAddress: state => state.sushiswapRouterAddress,
    sushiswapRouterContract: state => state.sushiswapRouterContract,
    meedContract: state => state.meedContract,
    wethContract: state => state.wethContract,
    meedAddress: state => state.meedAddress,
    wethAddress: state => state.wethAddress,
    etherBalance: state => state.etherBalance,
    meedsBalance: state => state.meedsBalance,
    transactionGas: state => state.transactionGas,
    meedsRouteAllowance: state => state.meedsRouteAllowance,
    provider: state => state.provider,
    loadingAmount() {
      return !!this.computingAmount || this.typing;
    },
    fromContract() {
      return this.buy && this.meedContract || this.wethContract;
    },
    tokenAdresses() {
      return this.buy && [this.wethAddress, this.meedAddress] || [this.meedAddress, this.wethAddress];
    },
    swapButtonLabel() {
      return this.buy && this.$t('buyMeeds') || this.$t('sellMeeds');
    },
    approveButtonLabel() {
      return this.sendingTransaction > 0 && this.$t('sellMeeds') || this.$t('approveMeeds');
    },
    disabledButton() {
      return !this.toValue || !this.isFromValueValid || !!this.sendingTransaction;
    },
    toValueDisplay() {
      return this.toValue && this.$ethUtils.toFixed(this.toValue, 8) || null;
    },
    fromValueValidator() {
      return [
        () => !!this.hasSufficientGas || this.$t('insufficientTransactionFee'),
        () => !!this.isFromValueNumeric || this.$t('valueMustBeNumeric'),
        () => !!this.hasSufficientFunds || this.$t('insufficientFunds'),
        () => !!this.isFromValueLessThanMax || this.$t('valueMustBeLessThan', {0: this.maxFromValueLabel}),
      ];
    },
    maxMeed() {
      if (this.meedsBalance) {
        const maxMeed = this.$ethUtils.fromDecimals(this.meedsBalance, 18);
        return Number(maxMeed);
      }
      return 0;
    },
    maxEther() {
      if (this.etherBalance && this.transactionGas) {
        const maxEther = this.$ethUtils.fromDecimals(this.etherBalance.sub(this.transactionGas), 18);
        return Number(maxEther) > 0 && Number(maxEther) || 0;
      }
      return 0;
    },
    maxFromValueLabel() {
      if (this.buy) {
        return this.$ethUtils.fromDecimals(this.etherBalance.sub(this.transactionGas), 18);
      } else {
        return this.$ethUtils.fromDecimals(this.meedsBalance, 18);
      }
    },
    isFromValueValid() {
      return !this.fromValue || (this.isFromValueNumeric && this.isFromValueLessThanMax && this.hasSufficientGas);
    },
    hasSufficientAllowedTokens() {
      if (this.buy || !this.isFromValueNumeric || !this.fromValue) {
        return true;
      } else {
        const meedsRouteAllowance = this.meedsRouteAllowance;
        const meedsToSend = this.$ethUtils.toDecimals(this.fromValue, 18);
        return meedsToSend.lte(meedsRouteAllowance);
      }
    },
    hasSufficientGas() {
      if (!this.fromValue) {
        return true;
      }
      if (this.etherBalance && this.transactionGas) {
        const maxEther = this.$ethUtils.fromDecimals(this.etherBalance.sub(this.transactionGas), 18);
        return Number(maxEther) > 0;
      }
      return false;
    },
    hasSufficientFunds() {
      if (!this.fromValue) {
        return true;
      }
      if (this.buy) {
        return this.maxEther > 0;
      } else {
        return this.maxMeed > 0;
      }
    },
    isFromValueLessThanMax() {
      if (!this.fromValue) {
        return true;
      }
      if (this.buy) {
        return Number(this.fromValue) <= this.maxEther;
      } else {
        return Number(this.fromValue) <= this.maxMeed;
      }
    },
    isFromValueNumeric() {
      if (!this.fromValue) {
        return true;
      }
      return this.fromValue && Number.isFinite(Number(this.fromValue));
    },
    step() {
      return this.sendingTransaction + 1;
    },
    canComputeValue() {
      return this.fromValue && this.isFromValueNumeric;
    },
    swapMethod() {
      if (this.provider && this.sushiswapRouterContract) {
        const signer = this.sushiswapRouterContract.connect(this.provider.getSigner());
        return this.buy && signer.swapExactETHForTokens || signer.swapExactTokensForETH;
      }
      return null;
    },
    approveMethod() {
      if (this.provider && this.meedContract) {
        const signer = this.meedContract.connect(this.provider.getSigner());
        return signer.approve;
      }
      return null;
    },
  }),
  watch: {
    meedsRouteAllowance() {
      if (this.swapInToSteps && this.meedsRouteAllowance && !this.meedsRouteAllowance.isZero()) {
        this.step = 2;
        this.sendingTransaction = 0;
      }
    },
    fromValue() {
      if (!this.fromValue) {
        this.computeValue();
        return;
      }
      this.startTypingKeywordTimeout = Date.now() + this.startSearchAfterInMilliseconds;
      if (!this.typing) {
        this.typing = true;
        this.waitForEndTyping();
      }
    },
  },
  methods: {
    reset() {
      this.fromValue = null;
      this.toValue = null;
      this.computeValue();
    },
    switchInputs() {
      this.buy = !this.buy;
      this.fromValue = this.toValue;
      this.toValue = null;
      this.computeValue();
    },
    waitForEndTyping() {
      window.setTimeout(() => {
        if (Date.now() > this.startTypingKeywordTimeout) {
          this.computeValue();
        } else {
          this.waitForEndTyping();
        }
      }, this.endTypingKeywordTimeout);
    },
    computeValue() {
      this.typing = false;
      if (!this.canComputeValue) {
        this.toValue = null;
      } else {
        this.computingAmount = true;
        this.toValue = null;
        const amountIn = this.$ethUtils.toDecimals(this.fromValue, 18);
        return this.sushiswapRouterContract.getAmountsOut(amountIn, this.tokenAdresses)
          .then(amounts =>  this.toValue = this.$ethUtils.fromDecimals(amounts[1], 18))
          .finally(() => this.computingAmount = false);
      }
    },
    sendSwapTransaction() {
      this.sendingTransaction++;
      const amountIn = this.$ethUtils.toDecimals(this.fromValue, 18);
      const amountOutMin = this.$ethUtils.toDecimals(this.toValue, 18)
        .mul((1 - this.slippage) * 1000)
        .div(1000);
      const options = {
        gasLimit: this.tradeGasLimit,
      };
      return new Promise((resolve, reject) => {
        if (this.buy) {
          options.value = amountIn.toHexString();
          return this.swapMethod(
            amountOutMin.toHexString(),
            this.tokenAdresses,
            this.address,
            this.getTransactionDeadline(),
            options,
          ).then(resolve).catch(reject);
        } else {
          return this.swapMethod(
            amountIn,
            amountOutMin.toHexString(),
            this.tokenAdresses,
            this.address,
            this.getTransactionDeadline(),
            options,
          ).then(resolve).catch(reject);
        }
      })
        .then(receipt => {
          const transactionHash = receipt.hash;
          this.$root.$emit('transaction-sent', transactionHash);
          this.reset();
        })
        .finally(() => {
          this.sendingTransaction--;
          this.swapInToSteps = false;
        });
    },
    sendApproveTransaction() {
      this.sendingTransaction++;
      const amount = this.$ethUtils.toDecimals(this.fromValue, 18);
      const options = {
        gasLimit: this.approvalGasLimit,
      };
      return this.approveMethod(
        this.sushiswapRouterAddress,
        amount,
        options
      ).then(receipt => {
        const transactionHash = receipt.hash;
        this.$root.$emit('transaction-sent', transactionHash);
        this.swapInToSteps = true;
      })
        .catch(() => {
          this.sendingTransaction--;
          this.step = 1;
        });
    },
    getTransactionDeadline() {
      return Date.now() + this.deadlineMinutes * 60 * 1000;
    },
    setMaxValue() {
      if (this.buy) {
        this.fromValue = this.$ethUtils.fromDecimals(this.etherBalance.sub(this.transactionGas), 18);
      } else {
        this.fromValue = this.$ethUtils.fromDecimals(this.meedsBalance, 18);
      }
    },
  },
};
</script>