"""
Canonical renderer — takes a `Resume` model and produces a single
canonical visual format DOCX (and via pdf_writer, the matching PDF).

The visual is locked. Every tailored resume looks identical:
- Header: name (20pt bold, centered) + contact (10pt, centered)
- Section headers: 11pt bold indigo, ALL CAPS, thin underline rule
- Role: title (11pt bold) + company·location (10pt italic gray) + dates (10pt italic gray)
- Bullets: 10.5pt, hanging indent, single line spacing
- Achievements: 3-5 quantified bullets
- Education: degree (bold) + institution·dates (italic gray)
- Skills: categorized SKILLS section (Tools, Methodologies, Domains, Core)
  placed after KEY ACHIEVEMENTS — the industry-standard ATS keyword vehicle.

NO sub-sections within roles.
"""

from __future__ import annotations
import os
import re
from docx import Document
from docx.shared import Pt, RGBColor, Inches
from docx.enum.text import WD_ALIGN_PARAGRAPH, WD_LINE_SPACING
from docx.oxml.ns import qn
from docx.oxml import OxmlElement

from .resume_model import Resume, Role, Education


# Colors used throughout — single source of truth
_NAME_COLOR = RGBColor(0x1A, 0x1A, 0x2E)   # near-black navy
_BODY_COLOR = RGBColor(0x1F, 0x29, 0x37)   # body text
_META_COLOR = RGBColor(0x55, 0x5B, 0x68)   # italic gray
_SECTION_COLOR = RGBColor(0x16, 0x48, 0x9E)  # indigo blue
_HR_LINE_COLOR = "16489E"


def render_resume_docx(resume: Resume, filepath: str) -> str:
    """
    Render the Resume model to a DOCX at filepath. Returns the filepath.

    Visual spec is fixed — every resume looks identical.
    """
    doc = Document()
    _set_page_margins(doc)
    _set_default_paragraph_style(doc)

    _write_header(doc, resume)
    _write_summary(doc, resume)
    _write_experience(doc, resume)
    _write_achievements(doc, resume)
    _write_skills(doc, resume)
    _write_education(doc, resume)

    os.makedirs(os.path.dirname(filepath), exist_ok=True)
    doc.save(filepath)
    return filepath


# ─────────────────────────────────────────────────────────────────────────
# Document setup
# ─────────────────────────────────────────────────────────────────────────

def _set_page_margins(doc: Document) -> None:
    for section in doc.sections:
        section.top_margin = Inches(0.6)
        section.bottom_margin = Inches(0.6)
        section.left_margin = Inches(0.7)
        section.right_margin = Inches(0.7)


def _set_default_paragraph_style(doc: Document) -> None:
    """Set the base style: Calibri 10.5pt, single-line spacing."""
    style = doc.styles["Normal"]
    style.font.name = "Calibri"
    style.font.size = Pt(10.5)
    style.paragraph_format.space_after = Pt(0)
    style.paragraph_format.line_spacing = 1.15


# ─────────────────────────────────────────────────────────────────────────
# Header (name + contact)
# ─────────────────────────────────────────────────────────────────────────

def _write_header(doc: Document, resume: Resume) -> None:
    name_para = doc.add_paragraph()
    name_para.alignment = WD_ALIGN_PARAGRAPH.CENTER
    name_para.paragraph_format.space_after = Pt(2)
    run = name_para.add_run(resume.name.upper())
    run.bold = True
    run.font.name = "Calibri"
    run.font.size = Pt(20)
    run.font.color.rgb = _NAME_COLOR

    contact_line = resume.contact.render_line()
    if contact_line:
        cp = doc.add_paragraph(contact_line)
        cp.alignment = WD_ALIGN_PARAGRAPH.CENTER
        cp.paragraph_format.space_after = Pt(6)
        for r in cp.runs:
            r.font.name = "Calibri"
            r.font.size = Pt(10)
            r.font.color.rgb = _META_COLOR

    # Thin horizontal rule under the header
    rule = doc.add_paragraph()
    rule.paragraph_format.space_after = Pt(6)
    _add_bottom_border(rule, size="6", color=_HR_LINE_COLOR)


# ─────────────────────────────────────────────────────────────────────────
# Sections
# ─────────────────────────────────────────────────────────────────────────

def _write_summary(doc: Document, resume: Resume) -> None:
    if not resume.summary:
        return
    _add_section_header(doc, "PROFESSIONAL SUMMARY")
    p = doc.add_paragraph(resume.summary)
    p.paragraph_format.space_after = Pt(6)
    p.paragraph_format.line_spacing = 1.25
    for r in p.runs:
        r.font.name = "Calibri"
        r.font.size = Pt(10.5)
        r.font.color.rgb = _BODY_COLOR


# Canonical casing for acronyms/brands so the Skills section reads correctly.
_SKILL_CASE = {
    "prd": "PRD", "prds": "PRDs", "saas": "SaaS", "api": "API", "apis": "APIs",
    "crm": "CRM", "ux": "UX", "ui": "UI", "kpi": "KPI", "kpis": "KPIs",
    "ga4": "GA4", "ai": "AI", "ml": "ML", "nlp": "NLP", "llm": "LLM",
    "llms": "LLMs", "ocr": "OCR", "qa": "QA", "sql": "SQL", "gtm": "GTM",
    "okr": "OKR", "okrs": "OKRs", "mvp": "MVP", "roi": "ROI", "cac": "CAC",
    "ltv": "LTV", "nps": "NPS", "arpu": "ARPU", "b2b": "B2B", "b2c": "B2C",
    "siem": "SIEM", "soar": "SOAR", "xdr": "XDR", "secops": "SecOps",
    "devops": "DevOps", "mlops": "MLOps", "plg": "PLG", "sso": "SSO",
    "fintech": "FinTech", "edtech": "EdTech", "martech": "MarTech",
    "healthtech": "HealthTech", "ecommerce": "eCommerce", "a/b testing": "A/B Testing",
    "power bi": "Power BI", "ga": "Google Analytics", "powerbi": "Power BI",
}

# Skill → category buckets (order = display order). A skill matches a bucket if
# it appears in that bucket's term set; anything else falls into "Core".
_TOOLS = {
    "jira", "confluence", "figma", "notion", "asana", "miro", "trello", "linear",
    "mixpanel", "amplitude", "ga4", "google analytics", "ga", "metabase",
    "tableau", "looker", "power bi", "powerbi", "sql", "excel", "spreadsheets",
    "segment", "hotjar", "salesforce", "hubspot", "webengage", "clevertap",
    "braze", "slack", "productboard", "airtable", "python",
}
_METHODS = {
    "agile", "scrum", "kanban", "lean", "sprint", "sprint planning", "okrs", "okr",
    "a/b testing", "experimentation", "experiments", "design thinking",
    "discovery", "roadmapping", "prioritization", "gtm", "go-to-market",
    "go-to-market strategy", "hypothesis testing", "user research",
    "agile methodologies", "backlog", "story mapping", "iteration",
    "performance tracking", "gap analysis", "competitive analysis",
    "competitor analysis", "market research", "benchmarking",
}
_DOMAINS = {
    "fintech", "edtech", "healthtech", "martech", "ecommerce", "saas", "b2b",
    "b2c", "lending", "credit", "insurance", "fraud", "banking", "payments",
    "logistics", "cybersecurity", "secops", "siem", "soar", "xdr",
}

# Recruiter-credible caps for the SKILLS section. A real skills block is a
# concise, scannable list — never a keyword dump. We cap each category line
# and the section total so the rendered DOCX reads like a human's resume.
_PER_CATEGORY_CAP = 10   # max items shown on a single category line
_SKILLS_TOTAL_CAP = 28   # max items across ALL categories combined


def _cap_skill(s: str) -> str:
    k = s.strip().lower()
    if k in _SKILL_CASE:
        return _SKILL_CASE[k]
    if "/" in k:
        return "/".join(p.capitalize() for p in k.split("/"))
    return " ".join(w.capitalize() for w in k.split())


def _write_skills(doc: Document, resume: Resume) -> None:
    """Categorized SKILLS section — the industry-standard ATS keyword vehicle.

    Groups the flat skill list into Tools, Methodologies, Domains, and Core
    Competencies, each rendered as EXACTLY ONE 'Category: a, b, c' line. Each
    category is capped at `_PER_CATEGORY_CAP` items and the section total at
    `_SKILLS_TOTAL_CAP`, so the block stays a concise, recruiter-credible list
    (never the repeated-header keyword dump). Surplus includable keywords are
    redirected into the Summary/Experience upstream, not rendered here.
    Placed after KEY ACHIEVEMENTS in the resume outline.
    """
    if not resume.skills:
        return
    # Dedup (case-insensitive), preserve order
    seen, flat = set(), []
    for s in resume.skills:
        k = s.strip().lower()
        if k and k not in seen:
            seen.add(k)
            flat.append(s.strip())

    buckets = {"Tools & Analytics": [], "Methodologies": [], "Domains": [], "Core Competencies": []}
    for s in flat:
        k = s.lower()
        if k in _TOOLS:
            buckets["Tools & Analytics"].append(s)
        elif k in _METHODS:
            buckets["Methodologies"].append(s)
        elif k in _DOMAINS:
            buckets["Domains"].append(s)
        else:
            buckets["Core Competencies"].append(s)

    # Cap BEFORE rendering: at most one line per category, and a recruiter-
    # credible section total. Each bucket is trimmed to _PER_CATEGORY_CAP, then
    # categories are filled in display order (Tools → Methods → Domains → Core)
    # until the running total hits _SKILLS_TOTAL_CAP — so an overlong "Core
    # Competencies" bucket is the first to lose its tail, keeping the section
    # reading like a real skills list. Overflow is intentionally DROPPED here;
    # important surplus terms are woven into Summary/Experience upstream.
    lines: list[tuple[str, list[str]]] = []
    running_total = 0
    for cat, items in buckets.items():
        if not items or running_total >= _SKILLS_TOTAL_CAP:
            continue
        capped = items[:_PER_CATEGORY_CAP]
        remaining = _SKILLS_TOTAL_CAP - running_total
        capped = capped[:remaining]
        if not capped:
            continue
        lines.append((cat, capped))
        running_total += len(capped)
    if not lines:
        return

    _add_section_header(doc, "SKILLS")
    for cat, items in lines:
        p = doc.add_paragraph()
        p.paragraph_format.space_after = Pt(2)
        label = p.add_run(f"{cat}: ")
        label.bold = True
        label.font.name = "Calibri"
        label.font.size = Pt(10.5)
        label.font.color.rgb = _NAME_COLOR
        body = p.add_run(", ".join(_cap_skill(x) for x in items))
        body.font.name = "Calibri"
        body.font.size = Pt(10.5)
        body.font.color.rgb = _BODY_COLOR


def _write_experience(doc: Document, resume: Resume) -> None:
    if not resume.roles:
        return
    _add_section_header(doc, "PROFESSIONAL EXPERIENCE")
    for role in resume.roles:
        _write_role(doc, role)


def _write_role(doc: Document, role: Role) -> None:
    # Role title — bold, 11pt
    title_para = doc.add_paragraph()
    title_para.paragraph_format.space_before = Pt(8)
    title_para.paragraph_format.space_after = Pt(0)
    run = title_para.add_run(role.title)
    run.bold = True
    run.font.name = "Calibri"
    run.font.size = Pt(11)
    run.font.color.rgb = _NAME_COLOR

    # Company · Location · Dates — italic gray, 10pt
    meta_parts = []
    if role.company:
        meta_parts.append(role.company)
    if role.location:
        meta_parts.append(role.location)
    if role.dates:
        meta_parts.append(role.dates)
    meta_text = " · ".join(meta_parts)
    if meta_text:
        meta_para = doc.add_paragraph()
        meta_para.paragraph_format.space_after = Pt(3)
        run = meta_para.add_run(meta_text)
        run.italic = True
        run.font.name = "Calibri"
        run.font.size = Pt(10)
        run.font.color.rgb = _META_COLOR

    # Bullets
    for bullet in role.bullets:
        p = doc.add_paragraph(style="List Bullet")
        p.paragraph_format.space_after = Pt(2)
        p.paragraph_format.left_indent = Inches(0.2)
        run = p.add_run(_clean_bullet_text(bullet))
        run.font.name = "Calibri"
        run.font.size = Pt(10.5)
        run.font.color.rgb = _BODY_COLOR


def _write_achievements(doc: Document, resume: Resume) -> None:
    if not resume.achievements:
        return
    _add_section_header(doc, "KEY ACHIEVEMENTS")
    for ach in resume.achievements:
        p = doc.add_paragraph(style="List Bullet")
        p.paragraph_format.space_after = Pt(2)
        p.paragraph_format.left_indent = Inches(0.2)
        run = p.add_run(_clean_bullet_text(ach))
        run.font.name = "Calibri"
        run.font.size = Pt(10.5)
        run.font.color.rgb = _BODY_COLOR


def _write_education(doc: Document, resume: Resume) -> None:
    if not resume.education:
        return
    _add_section_header(doc, "EDUCATION")
    for edu in resume.education:
        # Degree — bold 10.5pt
        deg_para = doc.add_paragraph()
        deg_para.paragraph_format.space_before = Pt(4)
        deg_para.paragraph_format.space_after = Pt(0)
        run = deg_para.add_run(edu.degree)
        run.bold = True
        run.font.name = "Calibri"
        run.font.size = Pt(10.5)
        run.font.color.rgb = _NAME_COLOR
        # Institution · Dates — italic gray
        meta_parts = []
        if edu.institution:
            meta_parts.append(edu.institution)
        if edu.dates:
            meta_parts.append(edu.dates)
        meta_text = " · ".join(meta_parts)
        if meta_text:
            ip = doc.add_paragraph()
            ip.paragraph_format.space_after = Pt(2)
            run = ip.add_run(meta_text)
            run.italic = True
            run.font.name = "Calibri"
            run.font.size = Pt(10)
            run.font.color.rgb = _META_COLOR


# ─────────────────────────────────────────────────────────────────────────
# Section header helper
# ─────────────────────────────────────────────────────────────────────────

def _add_section_header(doc: Document, title: str) -> None:
    """ALL-CAPS section header with thin indigo underline."""
    p = doc.add_paragraph()
    p.paragraph_format.space_before = Pt(10)
    p.paragraph_format.space_after = Pt(4)
    run = p.add_run(title.upper())
    run.bold = True
    run.font.name = "Calibri"
    run.font.size = Pt(11)
    run.font.color.rgb = _SECTION_COLOR
    _add_bottom_border(p)


def _add_bottom_border(paragraph, size: str = "6", color: str = _HR_LINE_COLOR) -> None:
    pPr = paragraph._p.get_or_add_pPr()
    pBdr = OxmlElement("w:pBdr")
    bottom = OxmlElement("w:bottom")
    bottom.set(qn("w:val"), "single")
    bottom.set(qn("w:sz"), size)
    bottom.set(qn("w:space"), "1")
    bottom.set(qn("w:color"), color)
    pBdr.append(bottom)
    pPr.append(pBdr)


# ─────────────────────────────────────────────────────────────────────────
# Helpers
# ─────────────────────────────────────────────────────────────────────────

def _clean_bullet_text(text: str) -> str:
    """Strip leading bullet chars and collapse whitespace."""
    s = re.sub(r"^[•\-–—*▪●\s]+", "", text)
    return re.sub(r"\s+", " ", s).strip()