From 26695a2509675a4548074e1e3ed32b9bd5922ea8 Mon Sep 17 00:00:00 2001
From: Tiago Amorim <tiago.andre.amorim@gmail.com>
Date: Wed, 29 May 2024 21:26:37 +0100
Subject: [PATCH] tweaked blueprint scheduling algorithm

---
 src/scheduler/handlers/blueprint_handler.rs | 48 +++---------------
 src/scheduler/mod.rs                        | 56 +++++++++++++--------
 2 files changed, 42 insertions(+), 62 deletions(-)

diff --git a/src/scheduler/handlers/blueprint_handler.rs b/src/scheduler/handlers/blueprint_handler.rs
index 54989c2..59e47d4 100644
--- a/src/scheduler/handlers/blueprint_handler.rs
+++ b/src/scheduler/handlers/blueprint_handler.rs
@@ -1,7 +1,4 @@
-use crate::{
-    db_api::{Item, Recipe},
-    scheduler::TIME_IN_DAY,
-};
+use crate::db_api::{Item, Recipe};
 
 use super::item_handler::{self};
 
@@ -25,40 +22,12 @@ impl ItemBlueprint {
         Ok(())
     }
 
-    pub fn schedule(
-        &mut self,
-        due_date: i32,
-        current_date: i32,
-    ) -> anyhow::Result<i32> {
-        let mut schedule_day = due_date;
-        let mut duration_acc = 0;
-
-        // walk back from the due date and find the
-        // last day that can accommodate each step in
-        // the process
-        for step in self.process.iter_mut() {
-            duration_acc += step.recipe.operation_time;
-            if duration_acc > TIME_IN_DAY {
-                schedule_day -= 1;
-                duration_acc = 0;
-            }
-
-            if schedule_day < current_date {
-                return Err(anyhow::anyhow!(
-                    "Cannot schedule item, due date is in the past"
-                ));
-            }
-
-            step.transf.set_date(schedule_day);
-
-            tracing::debug!(
-                "Scheduled transformation {:?} for day {}",
-                step.transf,
-                schedule_day
-            );
-        }
-
-        Ok(schedule_day)
+    pub fn set_start(&mut self, starting_date: i64) {
+        self.process
+            .last_mut()
+            .expect("empty process")
+            .transf
+            .set_date(starting_date as i32);
     }
 
     pub fn generate(
@@ -66,8 +35,7 @@ impl ItemBlueprint {
         full_recipe: &[Recipe],
     ) -> anyhow::Result<ItemBlueprint> {
         // for each item generate its components and
-        // transformations. Then schedule everything
-        // and update the item status to "Scheduled"
+        // transformations.
         let process =
             match item_handler::describe_process(full_recipe, item.clone()) {
                 Ok(proc) => proc,
diff --git a/src/scheduler/mod.rs b/src/scheduler/mod.rs
index 740e085..4004bb3 100644
--- a/src/scheduler/mod.rs
+++ b/src/scheduler/mod.rs
@@ -48,24 +48,15 @@ impl Scheduler {
         let current_date = {
             let mut con = pool.acquire().await?;
             db_api::get_date(&mut con).await?
-        };
+        } as i64;
+        // earliest start is the next day so that materials can be prepared
+        let earliest_start = current_date + 1;
 
-        let blueprints = order_items
+        let mut blueprints = order_items
             .iter()
             .filter_map(|item| {
-                let mut bp = match ItemBlueprint::generate(
-                    (*item).clone(),
-                    &full_recipe,
-                ) {
-                    Ok(bp) => bp,
-                    Err(e) => {
-                        tracing::error!("{:?}", e);
-                        return None;
-                    }
-                };
-
-                match bp.schedule(order.due_date(), current_date as i32) {
-                    Ok(_) => Some(bp),
+                match ItemBlueprint::generate((*item).clone(), &full_recipe) {
+                    Ok(bp) => Some(bp),
                     Err(e) => {
                         tracing::error!("{:?}", e);
                         None
@@ -73,16 +64,37 @@ impl Scheduler {
                 }
             })
             .collect::<Vec<_>>();
-
-        if blueprints.len() < order.quantity() as usize {
-            anyhow::bail!(
-                "Cannot fullfill order {:?}, can only schedule {:?}/{:?} parts",
-                order.id(),
-                blueprints.len(),
-                order.quantity()
+        assert_eq!(order_items.len(), blueprints.len());
+
+        //TODO: schedule the blueprints for production taking into account
+        //maximum factory parallelism capacity
+        let bp_time: i64 = full_recipe.iter().map(|r| r.operation_time).sum();
+
+        //TODO: make these constants config parameteres
+        //
+        // Assume that the factory can handle 3 blueprints in parallel at most
+        const PARALLELISM_CAPACITY: i64 = 3;
+        // assume a % of the needed time is spent on logistics instead of production
+        const LOGISTICS_TIME_FACTOR: i64 = 25;
+
+        // the last day that the order can be completed in order to be able to
+        // be delivered on time
+        let completion_date = order.due_date() as i64 - 1;
+        let bp_time = bp_time + bp_time * LOGISTICS_TIME_FACTOR / 100;
+        let total_time = bp_time * order.quantity() as i64;
+        let days_needed = total_time / (TIME_IN_DAY * PARALLELISM_CAPACITY);
+        if days_needed > completion_date - earliest_start {
+            tracing::warn!(
+                "Order {} cannot be completed on time, not enough capacity",
+                order.id()
             );
         }
 
+        let starting_date = earliest_start.max(completion_date - days_needed);
+        blueprints
+            .iter_mut()
+            .for_each(|bp| bp.set_start(starting_date));
+
         let mut tx = pool.begin().await?;
         for mut bp in blueprints {
             bp.insert_to_db(&mut tx).await?;