#include "runtime/runtime_spec_helper.h"
#include "runtime/parse_stack.h"
#include "runtime/tree.h"
#include "runtime/length.h"

enum {
  stateA, stateB, stateC, stateD, stateE, stateF, stateG, stageH
};

enum {
  symbol0 = ts_builtin_sym_start,
  symbol1, symbol2, symbol3, symbol4, symbol5, symbol6, symbol7
};

const char *symbol_names[] = {
  "ERROR", "END", "DOCUMENT", "AMBIGUITY",
  "zero", "one", "two", "three", "four", "five", "six", "seven",
};

START_TEST

describe("ParseStack", [&]() {
  ParseStack *stack;
  const size_t tree_count = 6;
  TSTree *trees[tree_count];

  before_each([&]() {
    stack = ts_parse_stack_new();
    TSLength len = ts_length_make(2, 2);
    for (size_t i = 0; i < tree_count; i++)
      trees[i] = ts_tree_make_leaf(ts_builtin_sym_start + i, len, len, false);
  });

  after_each([&]() {
    ts_parse_stack_delete(stack);
    for (size_t i = 0; i < tree_count; i++)
      ts_tree_release(trees[i]);
  });

  it("starts with a single null head", [&]() {
    AssertThat(ts_parse_stack_head_count(stack), Equals(1));
    AssertThat(ts_parse_stack_head(stack, 0), Equals<ParseStackNode *>(NULL));
  });

  describe("shift(head_index, state, tree)", [&]() {
    it("pushes a node with the given state and tree onto the given head", [&]() {
      ts_parse_stack_shift(stack, 0, 100, trees[0]);
      ts_parse_stack_shift(stack, 0, 101, trees[1]);
      ts_parse_stack_shift(stack, 0, 102, trees[2]);

      ParseStackNode *head = ts_parse_stack_head(stack, 0);
      AssertThat(head->state, Equals(102));
      AssertThat(head->tree, Equals(trees[2]));
      AssertThat(head->successor_count, Equals(1));

      head = head->successors[0];
      AssertThat(head->state, Equals(101));
      AssertThat(head->tree, Equals(trees[1]));
      AssertThat(head->successor_count, Equals(1));

      head = head->successors[0];
      AssertThat(head->state, Equals(100));
      AssertThat(head->tree, Equals(trees[0]));
      AssertThat(head->successor_count, Equals(1));

      head = head->successors[0];
      AssertThat(head, Equals<ParseStackNode *>(NULL));
    });
  });

  describe("reduce(head_index, state, symbol, child_count)", [&]() {
    before_each([&]() {
      ts_parse_stack_shift(stack, 0, 100, trees[0]);
      ts_parse_stack_shift(stack, 0, 101, trees[1]);
      ts_parse_stack_shift(stack, 0, 102, trees[2]);
    });

    it("replaces the given number of nodes with a single parent node", [&]() {
      ts_parse_stack_reduce(stack, 0, 103, symbol4, 2);

      ParseStackNode *head = ts_parse_stack_head(stack, 0);
      AssertThat(head->state, Equals(103));
      AssertThat(head->tree, Fulfills(EqualsTree(
        ts_tree_make_node(symbol4, 2, tree_array({ trees[1], trees[2] }), false),
        symbol_names)));
      AssertThat(head->successor_count, Equals(1));

      head = head->successors[0];
      AssertThat(head->state, Equals(100));
      AssertThat(head->tree, Equals(trees[0]));
      AssertThat(head->successor_count, Equals(1));
    });

    describe("when one of the reduced children is an 'extra' tree", [&]() {
      before_each([&]() {
        ts_tree_set_extra(trees[1]);
      });

      it("does not count that child toward the number of children to replace", [&]() {
        ts_parse_stack_reduce(stack, 0, 103, symbol4, 2);

        ParseStackNode *head = ts_parse_stack_head(stack, 0);
        AssertThat(head->state, Equals(103));
        AssertThat(head->tree, Fulfills(EqualsTree(
          ts_tree_make_node(symbol4, 3, tree_array({ trees[0], trees[1], trees[2] }), false),
          symbol_names)));
        AssertThat(head->successor_count, Equals(1));

        head = head->successors[0];
        AssertThat(head, Equals<ParseStackNode *>(NULL));
      });
    });
  });

  describe("split(head_index)", [&]() {
    int new_index;
    bool merged;

    before_each([&]() {
      //  A0__B1__C2
      ts_parse_stack_shift(stack, 0, stateA, trees[0]);
      ts_parse_stack_shift(stack, 0, stateB, trees[1]);
      ts_parse_stack_shift(stack, 0, stateC, trees[2]);

      new_index = ts_parse_stack_split(stack, 0);
      AssertThat(new_index, Equals(1));
      AssertThat(ts_parse_stack_head_count(stack), Equals(2));

      //  A0__B1__C2__D3
      //   \______E4__F3
      ts_parse_stack_shift(stack, 0, stateD, trees[3]);
      ts_parse_stack_reduce(stack, 1, stateE, symbol4, 2);
      merged = ts_parse_stack_shift(stack, 1, stateF, trees[3]);
    });

    it("creates a new head pointing to the same node as the given head", [&]() {
      AssertThat(merged, IsFalse());
      AssertThat(ts_parse_stack_head_count(stack), Equals(2));

      ParseStackNode *head1 = ts_parse_stack_head(stack, 0);
      AssertThat(head1->state, Equals(stateD));
      AssertThat(head1->tree, Equals(trees[3]));
      AssertThat(head1->successor_count, Equals(1));

      ParseStackNode *head2 = ts_parse_stack_head(stack, 1);
      AssertThat(head2->state, Equals(stateF));
      AssertThat(head2->tree, Equals(trees[3]));
      AssertThat(head2->successor_count, Equals(1));
    });

    describe("when the same state and tree are shifted onto both heads", [&]() {
      before_each([&]() {
        //  A0__B1__C2__D3__G5
        //   \______E4__F3__/
        merged = ts_parse_stack_shift(stack, 0, stateG, trees[5]);
        AssertThat(merged, IsFalse());
        merged = ts_parse_stack_shift(stack, 1, stateG, trees[5]);
        AssertThat(merged, IsTrue());
      });

      it("re-joins the heads", [&]() {
        AssertThat(ts_parse_stack_head_count(stack), Equals(1));

        ParseStackNode *head = ts_parse_stack_head(stack, 0);
        AssertThat(head->state, Equals(stateG));
        AssertThat(head->tree, Equals(trees[5]));
        AssertThat(head->successor_count, Equals(2));

        ParseStackNode *successor1 = head->successors[0];
        AssertThat(successor1->state, Equals(stateD));
        AssertThat(successor1->tree, Equals(trees[3]))
        AssertThat(successor1->successor_count, Equals(1));

        ParseStackNode *successor2 = head->successors[1];
        AssertThat(successor2->state, Equals(stateF));
        AssertThat(successor2->tree, Equals(trees[3]))
        AssertThat(successor2->successor_count, Equals(1));
      });
    });

    describe("when both heads are reduced into the same state with the same symbol and yield", [&]() {
      before_each([&]() {
        //  A0__G5
        merged = ts_parse_stack_reduce(stack, 0, stateG, symbol5, 3);
        AssertThat(merged, IsFalse());
        merged = ts_parse_stack_reduce(stack, 1, stateG, symbol5, 2);
        AssertThat(merged, IsTrue());
      });

      it("re-joins the heads, creating an 'ambiguity' node", [&]() {
        AssertThat(ts_parse_stack_head_count(stack), Equals(1));

        ParseStackNode *head = ts_parse_stack_head(stack, 0);
        AssertThat(head->state, Equals(stateG));

        AssertThat(head->tree, Fulfills(EqualsTree(
          ts_tree_make_ambiguity(2, tree_array({
            ts_tree_make_node(symbol5, 3, tree_array({
              trees[1],
              trees[2],
              trees[3],
            }), false),
            ts_tree_make_node(symbol5, 2, tree_array({
              ts_tree_make_node(symbol4, 2, tree_array({
                trees[1],
                trees[2],
              }), false),
              trees[3]
            }), false)
          })),
          symbol_names)));
        AssertThat(head->successor_count, Equals(1));
      });
    });
  });
});

END_TEST