"""Pydantic response/request schemas for the HTTP API.

Mirror the SQLAlchemy ORM but keep them de-coupled — the API surface is a
contract for the frontend; we don't want migrations to silently change
JSON shape.
"""
from __future__ import annotations

from datetime import date, datetime
from decimal import Decimal
from typing import Any

from pydantic import BaseModel, ConfigDict, Field


class _Base(BaseModel):
    model_config = ConfigDict(from_attributes=True)


# ── scenarios ────────────────────────────────────────────────────────


class ScenarioOut(_Base):
    id: int
    external_id: str
    kind: str
    name: str | None
    description: str | None
    parent_scenario_id: int | None
    jurisdiction: str
    strategy: str
    leave_uk_year: int
    glide_path: str
    spending_gbp: Decimal
    horizon_years: int
    nw_seed_gbp: Decimal
    savings_per_year_gbp: Decimal
    config_json: dict[str, Any]
    created_at: datetime


class ScenarioCreate(BaseModel):
    """Body for POST /scenarios — user-defined scenario."""
    name: str = Field(min_length=1, max_length=200)
    description: str | None = None
    parent_scenario_id: int | None = None
    jurisdiction: str
    strategy: str
    leave_uk_year: int = Field(ge=0, le=60)
    glide_path: str
    spending_gbp: Decimal = Field(gt=0)
    horizon_years: int = Field(ge=5, le=100, default=60)
    nw_seed_gbp: Decimal = Field(ge=0)
    savings_per_year_gbp: Decimal = Field(ge=0, default=Decimal("0"))
    config_json: dict[str, Any] = Field(default_factory=dict)


class ScenarioPatch(BaseModel):
    """Body for PATCH /scenarios/{id} — all fields optional."""
    name: str | None = None
    description: str | None = None
    jurisdiction: str | None = None
    strategy: str | None = None
    leave_uk_year: int | None = None
    glide_path: str | None = None
    spending_gbp: Decimal | None = None
    horizon_years: int | None = None
    nw_seed_gbp: Decimal | None = None
    savings_per_year_gbp: Decimal | None = None
    config_json: dict[str, Any] | None = None


# ── projections ──────────────────────────────────────────────────────


class ProjectionPoint(_Base):
    year_idx: int
    p10_portfolio_gbp: Decimal
    p25_portfolio_gbp: Decimal
    p50_portfolio_gbp: Decimal
    p75_portfolio_gbp: Decimal
    p90_portfolio_gbp: Decimal
    p50_withdrawal_gbp: Decimal
    p50_tax_gbp: Decimal
    survival_rate: Decimal


class GoalProbability(BaseModel):
    goal_id: int | None
    name: str
    kind: str
    probability: Decimal
    threshold: Decimal
    passed: bool


class ScenarioProjection(BaseModel):
    """Latest MC run + per-year fan-chart series for a scenario."""
    scenario_id: int
    external_id: str
    mc_run_id: int
    run_at: datetime
    n_paths: int
    success_rate: Decimal
    p10_ending_gbp: Decimal
    p50_ending_gbp: Decimal
    p90_ending_gbp: Decimal
    median_lifetime_tax_gbp: Decimal
    median_years_to_ruin: Decimal | None
    yearly: list[ProjectionPoint]
    goals_probability: list[GoalProbability] = Field(default_factory=list)


# ── net worth ────────────────────────────────────────────────────────


class AccountSnapshotOut(_Base):
    account_id: str
    account_name: str
    account_type: str
    currency: str
    snapshot_date: date
    market_value: Decimal
    market_value_gbp: Decimal
    cost_basis_gbp: Decimal | None


class NetWorthCurrent(BaseModel):
    """Snapshot at one point in time (latest by default)."""
    snapshot_date: date
    total_gbp: Decimal
    accounts: list[AccountSnapshotOut]


class NetWorthHistoryPoint(BaseModel):
    snapshot_date: date
    total_gbp: Decimal
    by_account: dict[str, Decimal]


class NetWorthHistory(BaseModel):
    """Per-day NW totals + per-account breakdown for a stacked area chart."""
    points: list[NetWorthHistoryPoint]


# ── annual spending (from actualbudget) ──────────────────────────────


class SpendingMonth(BaseModel):
    """One month's outflows (positive £) by category group, after
    income groups have been dropped upstream."""
    month: str  # "YYYY-MM"
    by_group: dict[str, Decimal]
    total_gbp: Decimal


class AnnualSpending(BaseModel):
    """Aggregated trailing-N-month spending pulled from actualbudget.

    `total_gbp` is the headline figure used as the "Annual spending"
    default in the WhatIf form. It is **inflation-adjusted to today's
    £** (each month's nominal pence revalued forward by
    `inflation_pct` compounded monthly), matching the simulator's
    real-£ convention.

    `nominal_total_gbp` is the same window without inflation
    adjustment — for transparency / comparison.

    `raw_total_gbp` is the nominal sum *including* groups that were
    excluded (e.g. investment transfers) — useful when you want to
    see your full cash outflow.
    """
    months: int
    window_start: str  # "YYYY-MM" (oldest month included)
    window_end: str    # "YYYY-MM" (newest)
    excluded_groups: list[str]
    inflation_pct: Decimal           # annual rate applied
    total_gbp: Decimal               # inflation-adjusted, after exclusions
    nominal_total_gbp: Decimal       # not adjusted, after exclusions
    raw_total_gbp: Decimal           # nominal, before exclusions
    by_group_total_gbp: dict[str, Decimal]  # nominal 12-mo group sums (incl. excluded)
    monthly: list[SpendingMonth]


# ── life events ──────────────────────────────────────────────────────


_CATEGORY_PATTERN = "^(essential|discretionary|not_spending)$"


class LifeEventOut(_Base):
    id: int
    scenario_id: int
    kind: str
    name: str
    year_start: int
    year_end: int | None
    delta_gbp_per_year: Decimal
    one_time_amount_gbp: Decimal | None
    category: str = "essential"
    enabled: bool
    payload: dict[str, Any] | None
    created_at: datetime


class LifeEventCreate(BaseModel):
    kind: str
    name: str = Field(min_length=1, max_length=200)
    year_start: int = Field(ge=0, le=100)
    year_end: int | None = Field(default=None, ge=0, le=100)
    delta_gbp_per_year: Decimal = Decimal("0")
    one_time_amount_gbp: Decimal | None = None
    category: str = Field(default="essential", pattern=_CATEGORY_PATTERN)
    enabled: bool = True
    payload: dict[str, Any] | None = None


class LifeEventPatch(BaseModel):
    kind: str | None = None
    name: str | None = None
    year_start: int | None = None
    year_end: int | None = None
    delta_gbp_per_year: Decimal | None = None
    one_time_amount_gbp: Decimal | None = None
    category: str | None = Field(default=None, pattern=_CATEGORY_PATTERN)
    enabled: bool | None = None
    payload: dict[str, Any] | None = None


# ── goals ────────────────────────────────────────────────────────────


class GoalOut(_Base):
    id: int
    scenario_id: int
    kind: str
    name: str
    target_amount_gbp: Decimal | None
    target_year: int | None
    comparator: str
    success_threshold: Decimal
    enabled: bool
    payload: dict[str, Any] | None
    created_at: datetime


class GoalCreate(BaseModel):
    kind: str
    name: str = Field(min_length=1, max_length=200)
    target_amount_gbp: Decimal | None = None
    target_year: int | None = Field(default=None, ge=0, le=100)
    comparator: str = ">="
    success_threshold: Decimal = Field(default=Decimal("0.95"), ge=0, le=1)
    enabled: bool = True
    payload: dict[str, Any] | None = None


# ── income streams ───────────────────────────────────────────────────


class IncomeStreamOut(_Base):
    id: int
    scenario_id: int
    kind: str
    name: str
    start_year: int
    end_year: int | None
    amount_gbp_per_year: Decimal
    growth_pct: Decimal
    tax_treatment: str
    enabled: bool
    payload: dict[str, Any] | None
    created_at: datetime


class IncomeStreamCreate(BaseModel):
    kind: str
    name: str = Field(min_length=1, max_length=200)
    start_year: int = Field(ge=0, le=100, default=0)
    end_year: int | None = Field(default=None, ge=0, le=100)
    amount_gbp_per_year: Decimal = Field(ge=0, default=Decimal("0"))
    growth_pct: Decimal = Field(default=Decimal("0"), ge=-1, le=1)
    tax_treatment: str = Field(default="income", pattern="^(income|dividend|cgt|tax_free)$")
    enabled: bool = True
    payload: dict[str, Any] | None = None


class IncomeStreamPatch(BaseModel):
    kind: str | None = None
    name: str | None = None
    start_year: int | None = None
    end_year: int | None = None
    amount_gbp_per_year: Decimal | None = None
    growth_pct: Decimal | None = None
    tax_treatment: str | None = None
    enabled: bool | None = None
    payload: dict[str, Any] | None = None


class IncomeStreamInput(BaseModel):
    """Engine-level income stream — same shape minus the row metadata."""
    kind: str = "salary"
    start_year: int = Field(ge=0, le=100, default=0)
    end_year: int | None = Field(default=None, ge=0, le=100)
    amount_gbp_per_year: Decimal = Field(ge=0, default=Decimal("0"))
    growth_pct: Decimal = Field(default=Decimal("0"))
    tax_treatment: str = Field(default="income", pattern="^(income|dividend|cgt|tax_free)$")
    enabled: bool = True


# ── year stats (per-year scrubber sidebar) ───────────────────────────


class YearStats(BaseModel):
    """Per-year metrics for the right-hand stats sidebar.

    Most fields derive from the latest persisted MC run + scenario
    config. Liquid NW / Expenses / Savings rate / Portfolio allocations
    are stubbed null until the relevant Wave 2 features land
    (real-estate split, expense streams, allocation editor).
    """
    year_idx: int
    calendar_year: int
    age: int | None
    net_worth_p50: Decimal
    change_in_nw: Decimal
    taxable_income: Decimal
    taxes: Decimal
    effective_tax_rate: Decimal
    spending: Decimal
    contributions: Decimal
    investment_growth: Decimal
    liquid_nw: Decimal | None = None
    expenses: Decimal | None = None
    savings_rate: Decimal | None = None
    portfolio_allocations: dict[str, Decimal] | None = None


# ── progress overlay (actuals vs projection) ─────────────────────────


class ProgressActualPoint(BaseModel):
    snapshot_date: date
    total_gbp: Decimal


class ProgressProjectedPoint(BaseModel):
    year_idx: int
    p10_portfolio_gbp: Decimal
    p50_portfolio_gbp: Decimal
    p90_portfolio_gbp: Decimal


class ProgressVariancePoint(BaseModel):
    year_idx: int
    actual_avg_gbp: Decimal
    projected_p50_gbp: Decimal
    delta_gbp: Decimal


class ProgressResponse(BaseModel):
    """`actual` is daily NW totals from `account_snapshot`. `projected`
    is the latest persisted fan in `projection_yearly`. `alignment_anchor`
    is the date corresponding to year_idx=0 — earliest snapshot or scenario
    `created_at` when no snapshots exist yet."""
    scenario_id: int
    alignment_anchor: date
    actual: list[ProgressActualPoint]
    projected: list[ProgressProjectedPoint]
    variance: list[ProgressVariancePoint]


# ── cashflow Sankey ──────────────────────────────────────────────────


class CashflowResponse(BaseModel):
    """Per-year sources/sinks for a Sankey diagram. Sums conserve at the
    Sankey level: total inflow == total outflow, with savings + ending-NW
    delta absorbing any leftover."""
    scenario_id: int
    year: int
    sources: dict[str, Decimal]
    sinks: dict[str, Decimal]


# ── simulate / compare ───────────────────────────────────────────────


class LifeEventInput(BaseModel):
    """Engine-level event shape — same as the DB row's relevant fields."""
    year_start: int = Field(ge=0, le=100)
    year_end: int | None = Field(default=None, ge=0, le=100)
    delta_gbp_per_year: Decimal = Decimal("0")
    one_time_amount_gbp: Decimal | None = None
    category: str = Field(default="essential", pattern=_CATEGORY_PATTERN)
    enabled: bool = True


class FlexRule(BaseModel):
    """ProjectionLab-style flex-spending rule.

    When the portfolio falls ``from_ath_pct`` below its running all-time-high,
    cut discretionary spending by ``cut_discretionary_pct``. Multiple rules
    stack via "worst applicable threshold wins" — at -30% from ATH a rule
    keyed at -10% AND a rule keyed at -25% both apply, but only the deeper
    cut takes effect (so users specify *cumulative* cuts, not per-tier).

    `from_ath_pct` is the absolute drop magnitude as a positive fraction:
    0.30 means "the portfolio is 30% below its ATH". This matches the way
    PLab labels its sliders ("if down 30%, cut 60%").
    """
    from_ath_pct: Decimal = Field(ge=0, le=1)
    cut_discretionary_pct: Decimal = Field(ge=0, le=1)


# ── spending profile ────────────────────────────────────────────────


class SpendingProfilePoint(BaseModel):
    year_idx: int
    base_gbp: Decimal
    essential_gbp: Decimal
    discretionary_gbp: Decimal
    not_spending_gbp: Decimal
    flex_cut_gbp: Decimal
    total_gbp: Decimal


class SpendingProfileResponse(BaseModel):
    scenario_id: int
    horizon_years: int
    points: list[SpendingProfilePoint]


class SimulateRequest(BaseModel):
    """Sync, non-persisted simulate. Used by the React UI for what-if.

    Allocation is hardcoded to 100% stocks at the engine layer
    (`api/simulate.py::_project`). The UI removed the glide-path knob
    in 2026-05; persisted Cartesian scenarios still carry their own
    `glide_path` string on the `scenario` table.
    """
    jurisdiction: str
    strategy: str
    leave_uk_year: int = Field(ge=0, le=60)
    spending_gbp: Decimal = Field(gt=0)
    nw_seed_gbp: Decimal = Field(ge=0)
    savings_per_year_gbp: Decimal = Decimal("0")
    horizon_years: int = Field(ge=5, le=100, default=60)
    floor_gbp: Decimal | None = None
    n_paths: int = Field(ge=100, le=50_000, default=5_000)
    seed: int = 42
    life_events: list[LifeEventInput] = Field(default_factory=list)
    # Returns model — controls how `paths` (n_paths × n_years × 3) is built:
    #   "shiller"     — block-bootstrap of Shiller 1871+ historical returns
    #                   (or the synthetic Shiller-calibrated stream when the
    #                   CSV isn't mounted). The default; broadest regime
    #                   coverage including 1929/1973/2000/2008.
    #   "manual"      — every year of every path = `manual_real_return_pct`.
    #                   Deterministic, no fan, useful for sanity checks.
    #   "wealthfolio" — block-bootstrap of the user's actual blended real
    #                   returns derived from wealthfolio_sync. Reflects the
    #                   recent regime only (~6 years). Glide path is moot.
    returns_mode: str = Field(default="shiller", pattern="^(shiller|manual|wealthfolio)$")
    manual_real_return_pct: Decimal | None = None
    income_streams: list[IncomeStreamInput] = Field(default_factory=list)
    goals: list[GoalCreate] = Field(default_factory=list)
    flex_rules: list[FlexRule] = Field(default_factory=list)
    # Rates settings (Wave 1.D.3). When `rates_mode='fixed'`, the engine
    # synthesises a deterministic real-return path from the per-asset
    # growth + dividend + inflation rates below, weighted by the static
    # 100% glide. `historical` falls back to Shiller bootstrap (legacy
    # `returns_mode` honoured when rates_mode is not set). `advanced` is
    # a Wave 2 stub.
    rates_mode: str | None = Field(default=None, pattern="^(fixed|historical|advanced)$")
    inflation_pct: Decimal = Field(default=Decimal("0.03"))
    stocks_growth_pct: Decimal = Field(default=Decimal("0.06"))
    stocks_dividend_pct: Decimal = Field(default=Decimal("0.025"))
    bonds_growth_pct: Decimal = Field(default=Decimal("0.015"))
    bonds_dividend_pct: Decimal = Field(default=Decimal("0.035"))
    stocks_allocation: Decimal = Field(default=Decimal("1.0"), ge=0, le=1)
    # Custom spending-plan parameters — only consulted when strategy="custom".
    # All real-£ / real-fraction. annual_real_adjust_pct = 0 means constant
    # real spending (Trinity-shape). Non-zero scales last year's withdrawal
    # multiplicatively each year (e.g. -0.005 for slow-down with age,
    # +0.02 for healthcare creep). Guardrail cuts spending by
    # `guardrail_cut_pct` whenever the portfolio falls below
    # `guardrail_threshold_pct` of its starting value; null disables.
    annual_real_adjust_pct: Decimal = Decimal("0")
    guardrail_threshold_pct: Decimal | None = None
    guardrail_cut_pct: Decimal = Decimal("0.10")


class SimulateResult(BaseModel):
    success_rate: Decimal
    p10_ending_gbp: Decimal
    p50_ending_gbp: Decimal
    p90_ending_gbp: Decimal
    median_lifetime_tax_gbp: Decimal
    median_years_to_ruin: Decimal | None
    elapsed_seconds: Decimal
    yearly: list[ProjectionPoint]
    goals_probability: list[GoalProbability] = Field(default_factory=list)


class CompareRequest(BaseModel):
    scenarios: list[SimulateRequest] = Field(min_length=2, max_length=5)


class CompareResult(BaseModel):
    results: list[SimulateResult]