#include "parser.h"
#include "../error/error.h"
#include "../utils/trim/trim.h"
#include <string>
#include <vector>

std::vector<Instruction> parse(std::string program) {
    std::vector<Instruction> instructions;
    std::vector<std::string> lines;
    std::string buf;
    int blockTracker = 0;

    for (char chr : program) {
        if (chr == '{') {
            blockTracker++;
        } else if (chr == '}') {
            if (blockTracker > 0) {
                blockTracker--;
            } else {
                error("Expected opening '{' to match closing '}'");
            }
        }

        if ((chr == '\n' || chr == ';') && blockTracker == 0) {
            if (!buf.empty()) {
                lines.push_back(buf);
                buf.clear();
            }
        } else {
            buf.push_back(chr);
        }
    }

    if (blockTracker != 0) {
        error("Expected closing '}' to match opening '{'");
    }
    if (!buf.empty()) {
        lines.push_back(buf);
    }

    for (std::string line : lines) {
        line = trim(line);
        if (line.empty()) {
            continue;
        }

        // Ignore commented lines
        if (line[0] == '#') {
            continue;
        }

        if (line.rfind("if", 0) == 0) {
            Instruction if_inst;
            if_inst.instruction = InstructionType::If;

            size_t block_start = line.find('{');
            if (block_start == std::string::npos) {
                error("Expected '{' for if statement");
                continue;
            }

            // 1. Condition
            std::string condition_str = line.substr(2, block_start - 2);
            if_inst.args.push_back(Value(Instruction(split(trim(condition_str)))));

            // 2. Find 'then' block
            size_t block_end = 0;
            int brace_level = 0;
            for (size_t i = block_start; i < line.length(); ++i) {
                if (line[i] == '{') brace_level++;
                else if (line[i] == '}') brace_level--;
                if (brace_level == 0) {
                    block_end = i;
                    break;
                }
            }
            if (block_end == 0) {
                error("Mismatched braces in if statement");
                continue;
            }

            std::string then_content = line.substr(block_start + 1, block_end - block_start - 1);
            if_inst.args.push_back(Value(parse(then_content))); // Recursive call

            // 3. Else block (optional)
            std::string remaining_line = trim(line.substr(block_end + 1));
            if (remaining_line.rfind("else", 0) == 0) {
                size_t else_block_start = remaining_line.find('{');
                if (else_block_start == std::string::npos) {
                    error("Expected '{' for else statement");
                    continue;
                }
                size_t else_block_end = remaining_line.find_last_of('}');
                 if (else_block_end == std::string::npos) {
                    error("Expected '}' for else statement");
                    continue;
                }
                std::string else_content = remaining_line.substr(else_block_start + 1, else_block_end - else_block_start - 1);
                if_inst.args.push_back(Value(parse(else_content)));
            }

            instructions.push_back(if_inst);
        } else if (line.rfind("while", 0) == 0) {
            Instruction while_inst;
            while_inst.instruction = InstructionType::While;

            size_t block_start = line.find('{');
            if (block_start == std::string::npos) {
                error("Expected '{' for while statement");
                continue;
            }

            // 1. Condition
            std::string condition_str = line.substr(5, block_start - 5);
            while_inst.args.push_back(Value(Instruction(split(trim(condition_str)))));

            // 2. Find 'then' block
            size_t block_end = 0;
            int brace_level = 0;
            for (size_t i = block_start; i < line.length(); ++i) {
                if (line[i] == '{') brace_level++;
                else if (line[i] == '}') brace_level--;
                if (brace_level == 0) {
                    block_end = i;
                    break;
                }
            }
            if (block_end == 0) {
                error("Mismatched braces in while statement");
                continue;
            }

            std::string then_content = line.substr(block_start + 1, block_end - block_start - 1);
            while_inst.args.push_back(Value(parse(then_content))); // Recursive call
            instructions.push_back(while_inst);
        } else if (line.rfind("fun", 0) == 0) {
            Instruction function_inst;
            function_inst.instruction = InstructionType::Function;

            size_t block_start = line.find('{');
            if (block_start == std::string::npos) {
                error("Expected '{' for function statement");
                continue;
            }

            // 1. Function signature (name + args)
            std::string signature_str = line.substr(3, block_start - 3);
            std::vector<Value> signature_parts = split(trim(signature_str));

            if (signature_parts.empty()) {
                error("Function definition is missing a name.");
                continue;
            }

            for(const auto& part : signature_parts) {
                function_inst.args.push_back(part);
            }

            // 2. Find 'then' block
            size_t block_end = 0;
            int brace_level = 0;
            for (size_t i = block_start; i < line.length(); ++i) {
                if (line[i] == '{') brace_level++;
                else if (line[i] == '}') brace_level--;
                if (brace_level == 0) {
                    block_end = i;
                    break;
                }
            }
            if (block_end == 0) {
                error("Mismatched braces in function statement");
                continue;
            }

            std::string then_content = line.substr(block_start + 1, block_end - block_start - 1);
            function_inst.args.push_back(Value(parse(then_content))); // Recursive call
            instructions.push_back(function_inst);
        } else {
            instructions.push_back(Instruction(split(line)));
        }
    }
    return instructions;
}