from __future__ import annotations

import html
from datetime import datetime
from pathlib import Path

from reportlab.lib import colors
from reportlab.lib.enums import TA_LEFT
from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import ParagraphStyle, getSampleStyleSheet
from reportlab.lib.units import cm
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.cidfonts import UnicodeCIDFont
from reportlab.platypus import (
    PageBreak,
    Paragraph,
    SimpleDocTemplate,
    Spacer,
    Table,
    TableStyle,
)

from .models import AgentResult, GeoPoint, RouteSolution, RouteTask, ToolEvent
from .solver import format_km, format_minutes


REPORT_DIR = Path("outputs")


def generate_pdf_report(
    task: RouteTask,
    points: list[GeoPoint],
    solution: RouteSolution,
    trace: list[ToolEvent],
    summary_markdown: str,
) -> str:
    REPORT_DIR.mkdir(parents=True, exist_ok=True)
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    path = REPORT_DIR / f"routeopt_report_{timestamp}.pdf"

    pdfmetrics.registerFont(UnicodeCIDFont("STSong-Light"))
    doc = SimpleDocTemplate(
        str(path),
        pagesize=A4,
        rightMargin=1.8 * cm,
        leftMargin=1.8 * cm,
        topMargin=1.6 * cm,
        bottomMargin=1.6 * cm,
        title="RouteOpt Agent 求解报告",
    )

    styles = make_styles()
    story: list = []

    story.append(Paragraph("RouteOpt Agent 求解报告", styles["TitleCJK"]))
    story.append(Paragraph(f"生成时间：{datetime.now().strftime('%Y-%m-%d %H:%M:%S')}", styles["BodyCJK"]))
    story.append(Spacer(1, 0.3 * cm))

    story.append(Paragraph("1. 问题定义", styles["HeadingCJK"]))
    story.extend(task_paragraphs(task, styles))
    story.append(Spacer(1, 0.2 * cm))

    story.append(Paragraph("2. 地点解析结果", styles["HeadingCJK"]))
    story.append(make_points_table(points))
    story.append(Spacer(1, 0.2 * cm))

    story.append(Paragraph("3. 优化结果", styles["HeadingCJK"]))
    story.extend(solution_paragraphs(solution, styles))
    story.append(make_leg_table(solution))
    story.append(Spacer(1, 0.2 * cm))

    story.append(Paragraph("4. Agent 工具调用轨迹", styles["HeadingCJK"]))
    story.append(make_trace_table(trace))

    story.append(PageBreak())
    story.append(Paragraph("5. 结果解释", styles["HeadingCJK"]))
    for paragraph in markdown_to_plain_paragraphs(summary_markdown):
        story.append(Paragraph(escape_for_pdf(paragraph), styles["BodyCJK"]))
        story.append(Spacer(1, 0.12 * cm))

    story.append(Paragraph("6. 局限性说明", styles["HeadingCJK"]))
    limitations = [
        "公开 API 可能存在限速、网络延迟或临时不可用；系统内置了上海示例地点和直线距离兜底策略。",
        "OSRM 公共服务适合课程演示和小规模样例，不建议用于商业高并发生产环境。",
        "本系统把大模型用于自然语言理解、工具调用规划和解释生成，把路线最优化交给确定性算法完成。",
    ]
    for item in limitations:
        story.append(Paragraph("• " + escape_for_pdf(item), styles["BodyCJK"]))

    doc.build(story)
    return str(path)


def make_styles() -> dict[str, ParagraphStyle]:
    base = getSampleStyleSheet()
    return {
        "TitleCJK": ParagraphStyle(
            "TitleCJK",
            parent=base["Title"],
            fontName="STSong-Light",
            fontSize=20,
            leading=26,
            alignment=TA_LEFT,
        ),
        "HeadingCJK": ParagraphStyle(
            "HeadingCJK",
            parent=base["Heading2"],
            fontName="STSong-Light",
            fontSize=14,
            leading=20,
            spaceBefore=8,
            spaceAfter=6,
        ),
        "BodyCJK": ParagraphStyle(
            "BodyCJK",
            parent=base["BodyText"],
            fontName="STSong-Light",
            fontSize=10.5,
            leading=16,
            wordWrap="CJK",
        ),
    }


def task_paragraphs(task: RouteTask, styles: dict[str, ParagraphStyle]) -> list[Paragraph]:
    destination_text = "、".join(task.destination_places)
    objective_text = "最短时间" if task.objective == "time" else "最短距离"
    return_text = "需要回到起点" if task.return_to_start else "不需要回到起点"
    fixed_end = task.fixed_end_place or "无"
    raw_request = task.raw_request or "用户通过结构化表单输入任务。"
    return [
        Paragraph(f"原始需求：{escape_for_pdf(raw_request)}", styles["BodyCJK"]),
        Paragraph(f"起点：{escape_for_pdf(task.start_place)}", styles["BodyCJK"]),
        Paragraph(f"目的地：{escape_for_pdf(destination_text)}", styles["BodyCJK"]),
        Paragraph(f"优化目标：{objective_text}；回程设置：{return_text}；固定终点：{escape_for_pdf(fixed_end)}", styles["BodyCJK"]),
    ]


def solution_paragraphs(solution: RouteSolution, styles: dict[str, ParagraphStyle]) -> list[Paragraph]:
    return [
        Paragraph(f"访问顺序：{escape_for_pdf(' → '.join(solution.route_names))}", styles["BodyCJK"]),
        Paragraph(
            f"总距离：{format_km(solution.total_distance_meters)}；预计驾驶时间：{format_minutes(solution.total_duration_seconds)}",
            styles["BodyCJK"],
        ),
        Paragraph(f"求解算法：{solution.algorithm}", styles["BodyCJK"]),
    ]


def make_points_table(points: list[GeoPoint]) -> Table:
    data = [["序号", "地点", "纬度", "经度", "数据源"]]
    for idx, point in enumerate(points):
        data.append([idx, point.name, f"{point.lat:.6f}", f"{point.lon:.6f}", point.source])
    table = Table(data, colWidths=[1.0 * cm, 4.3 * cm, 3.0 * cm, 3.0 * cm, 4.1 * cm])
    apply_table_style(table)
    return table


def make_leg_table(solution: RouteSolution) -> Table:
    data = [["段", "从", "到", "距离", "时间"]] + solution.leg_rows
    table = Table(data, colWidths=[1.0 * cm, 4.3 * cm, 4.3 * cm, 2.5 * cm, 2.5 * cm])
    apply_table_style(table)
    return table


def make_trace_table(trace: list[ToolEvent]) -> Table:
    data = [["步骤", "工具", "状态", "结果摘要"]]
    for event in trace:
        data.append([event.step, event.tool, event.status, event.result[:120]])
    table = Table(data, colWidths=[1.0 * cm, 4.0 * cm, 2.0 * cm, 8.6 * cm], repeatRows=1)
    apply_table_style(table)
    return table


def apply_table_style(table: Table) -> None:
    table.setStyle(
        TableStyle(
            [
                ("FONTNAME", (0, 0), (-1, -1), "STSong-Light"),
                ("FONTSIZE", (0, 0), (-1, -1), 8.5),
                ("BACKGROUND", (0, 0), (-1, 0), colors.HexColor("#eef2f7")),
                ("TEXTCOLOR", (0, 0), (-1, 0), colors.HexColor("#111827")),
                ("GRID", (0, 0), (-1, -1), 0.25, colors.HexColor("#d1d5db")),
                ("VALIGN", (0, 0), (-1, -1), "TOP"),
                ("ROWBACKGROUNDS", (0, 1), (-1, -1), [colors.white, colors.HexColor("#f8fafc")]),
            ]
        )
    )


def markdown_to_plain_paragraphs(markdown: str) -> list[str]:
    lines = []
    for line in markdown.splitlines():
        clean = line.strip()
        if not clean:
            continue
        clean = clean.replace("**", "")
        clean = clean.lstrip("#").strip()
        clean = clean.lstrip("-").strip()
        lines.append(clean)
    return lines or ["Agent 已完成路线优化并生成结构化结果。"]


def escape_for_pdf(text: str) -> str:
    return html.escape(str(text)).replace("\n", "<br/>")


def result_to_markdown(result: AgentResult) -> str:
    solution = result.solution
    return (
        f"**访问顺序**：{' → '.join(solution.route_names)}\n\n"
        f"**总距离**：{format_km(solution.total_distance_meters)}  \n"
        f"**预计时间**：{format_minutes(solution.total_duration_seconds)}\n\n"
        f"**算法**：{solution.algorithm}\n\n"
        f"{result.summary_markdown}"
    )