from backend.solver import LinearSolverEngine
from backend.linear_graph import LinearGraphPlotter
from flask import Flask, request, jsonify, render_template

app = Flask(__name__)


@app.route("/")
def index():
    return render_template("index.html")


@app.route("/ask", methods=["POST"])
def ask():
    question = request.form.get("question", "").strip()

    if not question:
        return jsonify({"error": "Please provide a question."}), 400

    if "=" not in question:
        return jsonify({"error": "Please enter a valid equation with '='"}), 400

    try:
        lhs, _, rhs = question.partition("=")

        engine = LinearSolverEngine(lhs, rhs, n=3)
        steps, solutions, var = engine.run()

        input_values = [p[0] for p in solutions]
        output_values = [p[1] for p in solutions]

        graph_plotter = LinearGraphPlotter(input_values, output_values)
        graph = graph_plotter.plot()

        response_text = (
            f"Let's solve your equation {lhs} = {rhs} step by step:\n\n"
            f"{steps}\n"
            f"Graph shows how solution changes with respect to '{var}'."
        )

        return jsonify({
            "answer": response_text,
            "graph": graph,
            "variable": str(var),
            "input_values": input_values,
            "output_values": output_values,
            "solutions": [
                {"input": str(p[0]), "output": str(p[1])}
                for p in solutions
            ]
        })

    except Exception as e:
        print(f"Error: {e}")
        return jsonify({
            "error": "An error occurred while processing your request."
        }), 500


if __name__ == "__main__":
    app.run(host="0.0.0.0", port=7860, debug=True)