Add Timestamp Validator contract

Introduce a new Timestamp Validator contract with basic functionality to validate timestamps. Updated the README to include deployment instructions for the new contract.

etc/contracts/README.md

@@ -52,6 +52,18 @@ Code hash 0x63a3ec45fd3ab905924a38227917e278de277c9b80d6865190d18d0d64f560bb
 Contract 5H6sLwXKBv3cdm5VVRxrvA8p5cux2Rrni5CQ4GRyYKo4b9B4
 ```
 
+#### Timestamp
+
+```text
+Code hash 0xee2250ba4215f273e571ecdfc2a373ccc96de5f82c19fcdaca889218fac5ac39
+Contract 5D35jFeQboveKiaQSxyLKENGqrnjgUc7B4D23QbhJK4Yr7jT
+```
+
+```shell
+cargo contract upload --url ws://127.0.0.1:9944 --suri //Alice timestamp_validator/target/ink/timestamp_validator.wasm
+cargo contract instantiate --url ws://127.0.0.1:9944 --suri //Alice timestamp_validator/target/ink/timestamp_validator.wasm --execute
+```
+
 ```shell
 cargo contract upload --url ws://127.0.0.1:9944 --suri //Alice geo_fence_contract/target/ink/geo_fence_contract.wasm
 cargo contract instantiate --url ws://127.0.0.1:9944 --suri //Alice geo_fence_contract/target/ink/geo_fence_contract.wasm --execute

etc/contracts/timestamp_validator/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "timestamp_validator"
+version = "0.1.0"
+authors = ["[your_name] <[your_email]>"]
+edition = "2021"
+
+[dependencies]
+ink = { version = "5.0.0", default-features = false }
+scale = { package = "parity-scale-codec", version = "3.6.12", default-features = false, features = ["derive"] }
+scale-info = { version = "2.11.3", default-features = false, features = ["derive"], optional = true }
+
+[dev-dependencies]
+ink_e2e = { version = "5.0.0" }
+
+[lib]
+path = "lib.rs"
+
+[features]
+default = ["std"]
+std = [
+    "ink/std",
+    "scale/std",
+    "scale-info/std",
+]
+ink-as-dependency = []
+e2e-tests = []

etc/contracts/timestamp_validator/lib.rs

@@ -0,0 +1,79 @@
+#![cfg_attr(not(feature = "std"), no_std, no_main)]
+#![allow(unexpected_cfgs)]
+#[ink::contract]
+mod timestamp_validator {
+    use scale::{Decode, Encode};
+
+    #[ink(storage)]
+    pub struct TimestampValidator {}
+
+    impl Default for TimestampValidator {
+        fn default() -> Self {
+            Self::new()
+        }
+    }
+
+    impl TimestampValidator {
+        #[ink(constructor)]
+        pub fn new() -> Self {
+            Self {}
+        }
+
+        #[ink(message)]
+        pub fn is_timestamp_valid(&self, timestamp: u64, start: u64, end: u64) -> bool {
+            // Check if timestamp is within range (inclusive)
+            timestamp >= start && timestamp <= end
+        }
+
+        #[ink(message)]
+        pub fn validate_with_error(&self, timestamp: u64, start: u64, end: u64) -> Result<(), Error> {
+            if timestamp < start {
+                return Err(Error::TooEarly);
+            }
+            if timestamp > end {
+                return Err(Error::TooLate);
+            }
+            Ok(())
+        }
+    }
+
+    #[derive(Debug, PartialEq, Eq, Encode, Decode)]
+    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
+    pub enum Error {
+        TooEarly,
+        TooLate,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::timestamp_validator::{Error, TimestampValidator};
+
+    #[ink::test]
+    fn test_timestamp_validation() {
+        let validator = TimestampValidator::new();
+
+        // Test valid timestamp
+        assert!(validator.is_timestamp_valid(100, 50, 150));
+
+        // Test boundary conditions
+        assert!(validator.is_timestamp_valid(50, 50, 150)); // Start boundary
+        assert!(validator.is_timestamp_valid(150, 50, 150)); // End boundary
+
+        // Test invalid timestamps
+        assert!(!validator.is_timestamp_valid(49, 50, 150)); // Before start
+        assert!(!validator.is_timestamp_valid(151, 50, 150)); // After end
+    }
+
+    #[ink::test]
+    fn test_validate_with_error() {
+        let validator = TimestampValidator::new();
+
+        // Test valid timestamp
+        assert_eq!(validator.validate_with_error(100, 50, 150), Ok(()));
+
+        // Test invalid timestamps
+        assert_eq!(validator.validate_with_error(49, 50, 150), Err(Error::TooEarly));
+        assert_eq!(validator.validate_with_error(151, 50, 150), Err(Error::TooLate));
+    }
+}