🏋️ Day 10 of #30DaysOfSolidity — Building a Decentralized Fitness Tracker with Events & Milestones

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.19;



/// @title FitTrack - A Decentralized Fitness Tracker

/// @author Saurav

/// @notice Log your workouts and unlock fitness milestones on-chain

/// @dev Demonstrates event indexing, mappings, and user data tracking

contract FitTrack {

    struct Workout {

        string workoutType;

        uint256 duration; // in minutes

        uint256 calories;

        uint256 timestamp;

    }



    struct UserStats {

        uint256 totalWorkouts;

        uint256 totalMinutes;

        uint256 totalCalories;

        uint256 lastWeekWorkouts;

        uint256 lastWeekStart;

    }



    mapping(address => Workout[]) private workouts;

    mapping(address => UserStats) public userStats;



    /// @notice Emitted when a workout is logged

    event WorkoutLogged(address indexed user, string workoutType, uint256 duration, uint256 calories);



    /// @notice Emitted when user reaches 10 workouts in a week

    event WeeklyGoalReached(address indexed user, uint256 workoutsCount);



    /// @notice Emitted when user reaches 500 total minutes milestone

    event TotalMinutesMilestone(address indexed user, uint256 totalMinutes);



    /// @dev Log a workout session

    function logWorkout(string memory _type, uint256 _duration, uint256 _calories) external {

        require(_duration > 0, "Duration must be greater than 0");



        Workout memory newWorkout = Workout({

            workoutType: _type,

            duration: _duration,

            calories: _calories,

            timestamp: block.timestamp

        });



        workouts[msg.sender].push(newWorkout);

        UserStats storage stats = userStats[msg.sender];



        stats.totalWorkouts += 1;

        stats.totalMinutes += _duration;

        stats.totalCalories += _calories;



        // Weekly logic

        if (block.timestamp > stats.lastWeekStart + 7 days) {

            stats.lastWeekStart = block.timestamp;

            stats.lastWeekWorkouts = 0;

        }



        stats.lastWeekWorkouts += 1;



        emit WorkoutLogged(msg.sender, _type, _duration, _calories);



        // Check milestones

        if (stats.lastWeekWorkouts == 10) {

            emit WeeklyGoalReached(msg.sender, stats.lastWeekWorkouts);

        }



        if (stats.totalMinutes >= 500 && (stats.totalMinutes - _duration) < 500) {

            emit TotalMinutesMilestone(msg.sender, stats.totalMinutes);

        }

    }



    /// @notice Get all workouts of a user

    function getWorkouts(address _user) external view returns (Workout[] memory) {

        return workouts[_user];

    }



    /// @notice Get user's current stats

    function getUserStats(address _user) external view returns (UserStats memory) {

        return userStats[_user];

    }

}