From 3ebf4f78993392cbbdd0fe2c04db175e4df23e2d Mon Sep 17 00:00:00 2001
From: Sosthene <contact@sosthene.net>
Date: Fri, 4 Oct 2024 09:25:58 +0200
Subject: [PATCH] Add validation logic to ProcessState

---
 src/process.rs | 78 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 77 insertions(+), 1 deletion(-)

diff --git a/src/process.rs b/src/process.rs
index f837c37..653c116 100644
--- a/src/process.rs
+++ b/src/process.rs
@@ -11,7 +11,83 @@ pub struct ProcessState {
     pub commited_in: OutPoint,
     pub encrypted_pcd: Value, // Some fields may be clear, if the owner of the process decides so
     pub keys: Map<String, Value>, // We may not always have all the keys
-    pub validation_token: Vec<Proof>, // This signs the encrypted pcd
+    pub validation_tokens: Vec<Proof>, // Signature of the hash of the encrypted pcd tagged with some decision like "yes" or "no"
+}
+
+impl ProcessState {
+    /// A state is valid if the attached validation_tokens satisfy the updated conditions defined in the encrypted_pcd
+    pub fn is_valid(&self, previous_state: Option<&ProcessState>) -> Result<bool, anyhow::Error> {
+        // Determine modified fields
+        let modified_fields: Vec<String> = if let Some(previous_state) = previous_state 
+        {
+            let res: Vec<String> = self.encrypted_pcd.as_object().unwrap()
+            .iter()
+            .filter_map(|(key, value)| {
+                let previous_value = previous_state.encrypted_pcd.get(key);
+                if previous_value.is_none() || value != previous_value.unwrap() {
+                    Some(key.clone())
+                } else {
+                    None
+                }
+            })
+            .collect();
+
+            if res.is_empty() {
+                return Err(anyhow::anyhow!("State is identical to the previous state"));
+            }
+
+            res
+        } else {
+            self.encrypted_pcd.as_object().unwrap()
+                .keys()
+                .cloned()
+                .collect()
+        };
+
+        // Extract roles and their definitions
+        let mut fields2plains = Map::new();
+        self.encrypted_pcd.decrypt_fields(&self.keys, &mut fields2plains)?;
+
+        let mut roles2rules: HashMap<String, RoleDefinition> = HashMap::new();
+        if let Some(roles) = fields2plains.get("roles") {
+            if roles.is_null() {
+                return Err(anyhow::anyhow!("Can't decrypt roles in the encrypted pcd"));
+            }
+            if let Some(roles_map) = roles.as_object() {
+                for (role, conditions) in roles_map {
+                    let role_def = serde_json::from_value::<RoleDefinition>(conditions.clone())?;
+                    roles2rules.insert(role.to_string(), role_def);
+                }
+            } else {
+                return Err(anyhow::anyhow!("Roles is not an object"));
+            }
+        } else {
+            return Err(anyhow::anyhow!("Missing roles in the encrypted pcd"));
+        }
+
+        // Check if each modified field satisfies at least one applicable rule across all roles
+        let all_fields_validated = modified_fields.iter().all(|field| {
+            let applicable_rules: Vec<(&RoleDefinition, &ValidationRule)> = roles2rules.values()
+                .flat_map(|role_def| {
+                    role_def.get_applicable_rules(field)
+                        .into_iter()
+                        .map(move |rule| (role_def, rule))
+                })
+                .collect();
+
+            if applicable_rules.is_empty() {
+                return false; // No rules apply to this field, consider it invalid
+            }
+
+            let validation_tokens: Vec<&Proof> = self.validation_tokens.iter().collect();
+
+            applicable_rules.into_iter().any(|(role_def, rule)| {
+                rule.is_satisfied(field, AnkPcdHash::from_value(&self.encrypted_pcd), &validation_tokens, &role_def.members)
+            })
+        });
+
+        Ok(all_fields_validated)
+    }
 }
 
 /// A process is basically a succession of states