From 04b5ed7c4f7f899cea256fabfdeb3d43cbe877c7 Mon Sep 17 00:00:00 2001
From: Green Sky <green@g-s.xyz>
Date: Wed, 14 Dec 2022 14:56:54 +0100
Subject: [PATCH] add ops, start on text diffing and op gernation, no diffing
 yet

---
 version0/list.hpp          |  14 ++++
 version0/text_document.hpp | 129 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 142 insertions(+), 1 deletion(-)

diff --git a/version0/list.hpp b/version0/list.hpp
index e6ba7dd..8c4ca31 100644
--- a/version0/list.hpp
+++ b/version0/list.hpp
@@ -35,6 +35,20 @@ struct List {
 		}
 	};
 
+	// almost the same as entry
+	struct OpAdd {
+		ListID id;
+
+		std::optional<ListID> parent_left;
+		std::optional<ListID> parent_right;
+
+		ValueType value;
+	};
+
+	struct OpDel {
+		ListID id;
+	};
+
 	// TODO: replace with SoA
 	struct Entry {
 		ListID id;
diff --git a/version0/text_document.hpp b/version0/text_document.hpp
index 1fc626d..072ae43 100644
--- a/version0/text_document.hpp
+++ b/version0/text_document.hpp
@@ -2,6 +2,10 @@
 
 #include "./list.hpp"
 
+#include <optional>
+#include <variant>
+#include <vector>
+
 namespace GreenCRDT {
 
 template<typename AgentType>
@@ -9,14 +13,18 @@ struct TextDocument {
 	// TODO: determine if char is the best
 	using ListType = List<char, AgentType>;
 
+	using Op = std::variant<typename ListType::OpAdd, typename ListType::OpDel>;
+
 	struct Cursor {
 		AgentType who;
 		typename ListType::ListID pos;
 	};
 
+	AgentType local_agent;
+
 	ListType state;
 
-	std::string getText(void) {
+	[[nodiscard]] std::string getText(void) const {
 		std::string text;
 
 		for (const auto& it : state.list) {
@@ -27,6 +35,125 @@ struct TextDocument {
 
 		return text;
 	}
+
+	static std::vector<Op> text2adds(
+		const AgentType& agent, uint64_t& last_seq,
+		std::optional<typename ListType::ListID> parent_left,
+		std::optional<typename ListType::ListID> parent_right,
+		std::string_view text
+	) {
+		std::vector<Op> ops;
+		for (size_t i = 0; i < text.size(); i++) {
+			typename ListType::ListID new_id {agent, ++last_seq};
+
+			ops.emplace_back(typename ListType::OpAdd{
+				new_id,
+				parent_left,
+				parent_right,
+				text[i]
+			});
+
+			parent_left = new_id;
+		}
+
+		return ops;
+	}
+
+	// adds in tast with specified parents
+	// returns generated ops
+	std::vector<Op> addText(
+		std::optional<typename ListType::ListID> parent_left,
+		std::optional<typename ListType::ListID> parent_right,
+		std::string_view text
+	) {
+		// TODO: look up typesystem and fix (move? decltype?)
+		std::vector<Op> ops = text2adds(
+			local_agent, state.last_seen_seq[local_agent],
+			parent_left,
+			parent_right,
+			text
+		);
+
+		// TODO: make this better
+		// and apply
+		for (const auto& op : ops) {
+			if constexpr (std::holds_alternative<typename ListType::OpAdd>(op)) {
+				const auto& add_op = std::get<typename ListType::OpAdd>(op);
+				state.add(add_op.id, add_op.value, add_op.parent_left, add_op.parent_right);
+			} else if constexpr (std::holds_alternative<typename ListType::OpDel>(op)) {
+				const auto& del_op = std::get<typename ListType::OpDel>(op);
+				state.del(del_op.id);
+			} else {
+				assert(false);
+			}
+		}
+
+		return ops; // TODO: move?
+	}
+
+	// deletes everything in range [first, last)
+	// returns generated ops
+	std::vector<Op> delRange(
+		std::optional<typename ListType::ListID> left,
+		std::optional<typename ListType::ListID> right
+	) {
+		size_t first_idx = 0;
+		if (left.has_value()) {
+			auto res = state.findIdx(left.value());
+			if (!res.has_value()) {
+				assert(false && "cant find left");
+				return {};
+			}
+			first_idx = res;
+		}
+
+		size_t last_idx = state.list.size();
+		if (right.has_value()) {
+			auto res = state.findIdx(right.value());
+			if (!res.has_value()) {
+				assert(false && "cant find right");
+				return {};
+			}
+			last_idx = res;
+		}
+
+		std::vector<Op> ops;
+
+		for (size_t i = first_idx; i < last_idx; i++) {
+			ops.emplace_back(typename ListType::OpDel{
+				state.list[i].id
+			});
+
+			// TODO: do delets get a seq?????
+
+			state.list[i].value = std::nullopt;
+		}
+
+		return ops;
+	}
+
+	// generates ops from the difference
+	// note: rn it only creates 1 diff patch
+	std::vector<Op> merge(std::string_view other_text) {
+		if (other_text.empty()) {
+			return {};
+		}
+
+		if (state.list.empty()) {
+			return addText(
+				std::nullopt,
+				std::nullopt,
+				other_text
+			);
+		}
+
+		// find start and end of changes
+		// start
+		size_t list_idx_start = 0;
+		size_t other_idx_start = 0;
+		//for (; idx_start < state.list.size(); idx_start++) {}
+
+	}
 };
 
 } // GreenCRDT