import os
from pathlib import Path
import sys

os.environ.setdefault("MPLCONFIGDIR", "/tmp/matplotlib")

import schemdraw
import schemdraw.elements as elm
from schemdraw.segments import SegmentText

FONT_NAME = "STIXGeneral"
BG_COLOR = "white"
DEFAULT_OUTPUT = Path(__file__).resolve().parent.parent / "image" / "target_circuit.svg"


def add_text(
    drawing,
    position,
    text,
    *,
    fontsize=18,
    rotation=0,
    align=("center", "center"),
):
    element = elm.Element().at(position).anchor("center").hold()
    element.anchors["center"] = (0, 0)
    element.segments.append(
        SegmentText(
            (0, 0),
            text,
            rotation=rotation,
            align=align,
            fontsize=fontsize,
            font=FONT_NAME,
        )
    )
    drawing.add(element)


def draw_circuit(save_path=DEFAULT_OUTPUT):
    save_path = Path(save_path)
    save_path.parent.mkdir(parents=True, exist_ok=True)

    with schemdraw.Drawing(show=False) as d:
        d.config(
            unit=1.0,
            fontsize=18,
            font=FONT_NAME,
            lw=2.2,
            margin=0.2,
            bgcolor=BG_COLOR,
        )

        # 关键节点，整体布局按参考图重排。
        a_node = (1.4, 4.0)
        top_node = (5.2, 6.6)
        bottom_node = (5.2, 1.9)
        right_node = (9.3, 4.0)
        bottom_left = (1.4, 0.8)
        top_term = (10.9, 4.0)
        bottom_term = (10.9, 1.9)

        source_start = (4.8, 0.8)
        source_len = 1.6
        source_end = (source_start[0] + source_len, source_start[1])

        # 主电路元件
        d.add(elm.ResistorIEC().at(a_node).to(top_node).hold())
        d.add(elm.ResistorIEC().at(a_node).to(bottom_node).hold())
        d.add(elm.ResistorIEC().at(top_node).to(right_node).hold())
        d.add(elm.Source().at(bottom_node).up(top_node[1] - bottom_node[1]).hold())
        d.add(elm.ResistorIEC().at(bottom_left).up(a_node[1] - bottom_left[1]).hold())

        # 下方电压源支路
        d.add(elm.Line().at(bottom_left).right(source_start[0] - bottom_left[0]).hold())
        d.add(elm.Source().at(source_start).right(source_len).hold())
        d.add(elm.Line().at(source_end).right(right_node[0] - source_end[0]).hold())

        # 右侧导线与端子
        d.add(elm.Line().at(right_node).right(top_term[0] - right_node[0]).hold())
        d.add(elm.Line().at(right_node).down(right_node[1] - source_start[1]).hold())
        d.add(elm.Line().at(bottom_node).right(bottom_term[0] - bottom_node[0]).hold())

        # 电流源符号细节：空心圆、内部横线、外部向上箭头。
        source_center_y = (top_node[1] + bottom_node[1]) / 2
        d.add(elm.Line().at((4.74, source_center_y)).right(0.92).hold())
        d.add(elm.Arrow().at((5.2, 4.9)).up(1.0).hold())

        # 电压源符号细节：圆内水平线。
        d.add(elm.Line().at(source_start).right(source_len).hold())

        # 节点和开口端子
        for point in [a_node, top_node, bottom_node, right_node]:
            d.add(elm.Dot(radius=0.085).at(point).hold())

        d.add(elm.Dot(open=True, radius=0.1).at(top_term).hold())
        d.add(elm.Dot(open=True, radius=0.1).at(bottom_term).hold())

        # 文本标注
        add_text(d, (2.35, 5.18), r"$R_1$", fontsize=19)

        add_text(d, (8.78, 5.12), r"$R_3$", fontsize=19)

        add_text(d, (2.42, 2.62), r"$R_2$", fontsize=19)

        add_text(d, (0.55, 1.28), r"$R_4$", fontsize=19)

        add_text(d, (6.42, 4.82), r"$I_S$", fontsize=19)

        add_text(d, (4.3, 0.36), "-", fontsize=21)
        add_text(d, (6.98, 0.36), "+", fontsize=21)
        add_text(d, (4.78, -0.05), r"$U_S$", fontsize=19)

        d.save(str(save_path), transparent=False)

    print(f"saved to: {save_path}")


if __name__ == "__main__":
    output_path = sys.argv[1] if len(sys.argv) > 1 else DEFAULT_OUTPUT
    draw_circuit(output_path)