from __future__ import annotations

import re
from typing import Literal

from pydantic import BaseModel, ConfigDict, Field, field_validator


IntentType = Literal["CODE_QA", "DOCS_QA", "GENERATE_DOCS_FROM_CODE", "PROJECT_MISC"]
ConversationMode = Literal["START", "CONTINUE", "SWITCH"]
AnchorType = Literal["FILE_PATH", "SYMBOL", "DOC_REF", "KEY_TERM"]
AnchorSource = Literal["user_text", "conversation_state", "heuristic"]
_INLINE_CODE_RE = re.compile(r"`([^`]*)`")
_CODE_SYMBOL_RE = re.compile(r"\b([A-Za-z_][A-Za-z0-9_]{2,})\b")


class AnchorSpan(BaseModel):
    model_config = ConfigDict(extra="forbid")

    start: int = 0
    end: int = 0


class QueryAnchor(BaseModel):
    model_config = ConfigDict(extra="forbid")

    type: AnchorType
    value: str
    source: AnchorSource = "user_text"
    subtype: str | None = None
    span: AnchorSpan | None = None
    confidence: float = 0.0

    @field_validator("confidence")
    @classmethod
    def clamp_confidence(cls, value: float) -> float:
        return max(0.0, min(1.0, float(value)))


class QueryPlan(BaseModel):
    model_config = ConfigDict(extra="forbid")

    raw: str
    normalized: str
    sub_intent: str = "EXPLAIN"
    negations: list[str] = Field(default_factory=list)
    expansions: list[str] = Field(default_factory=list)
    keyword_hints: list[str] = Field(default_factory=list)
    anchors: list[QueryAnchor] = Field(default_factory=list)


class LayerQuery(BaseModel):
    model_config = ConfigDict(extra="forbid")

    layer_id: str
    top_k: int


class CodeRetrievalFilters(BaseModel):
    model_config = ConfigDict(extra="forbid")

    test_policy: str = "EXCLUDE"
    path_scope: list[str] = Field(default_factory=list)
    language: list[str] = Field(default_factory=list)


class DocsRetrievalFilters(BaseModel):
    model_config = ConfigDict(extra="forbid")

    path_scope: list[str] = Field(default_factory=list)
    doc_kinds: list[str] = Field(default_factory=list)
    doc_language: list[str] = Field(default_factory=list)


class HybridRetrievalFilters(BaseModel):
    model_config = ConfigDict(extra="forbid")

    test_policy: str = "EXCLUDE"
    path_scope: list[str] = Field(default_factory=list)
    language: list[str] = Field(default_factory=list)
    doc_kinds: list[str] = Field(default_factory=list)
    doc_language: list[str] = Field(default_factory=list)


class RetrievalSpec(BaseModel):
    model_config = ConfigDict(extra="forbid")

    domains: list[str] = Field(default_factory=list)
    layer_queries: list[LayerQuery] = Field(default_factory=list)
    filters: CodeRetrievalFilters | DocsRetrievalFilters | HybridRetrievalFilters = Field(default_factory=CodeRetrievalFilters)
    rerank_profile: str = ""


class EvidencePolicy(BaseModel):
    model_config = ConfigDict(extra="forbid")

    require_def: bool = False
    require_flow: bool = False
    require_spec: bool = False
    allow_answer_without_evidence: bool = False


class IntentRouterResult(BaseModel):
    model_config = ConfigDict(extra="forbid")

    schema_version: str = "1.1"
    intent: IntentType
    graph_id: str
    conversation_mode: ConversationMode
    query_plan: QueryPlan
    retrieval_spec: RetrievalSpec
    evidence_policy: EvidencePolicy


class ConversationState(BaseModel):
    model_config = ConfigDict(extra="forbid")

    active_intent: IntentType | None = None
    active_domain: str | None = None
    active_anchors: list[QueryAnchor] = Field(default_factory=list)
    active_symbol: str | None = None
    active_path_scope: list[str] = Field(default_factory=list)
    active_code_span_symbols: list[str] = Field(default_factory=list)
    last_query: str = ""
    turn_index: int = 0

    def advance(self, result: IntentRouterResult) -> "ConversationState":
        user_anchors = [anchor for anchor in result.query_plan.anchors if anchor.source == "user_text"]
        symbol_candidates = [anchor.value for anchor in user_anchors if anchor.type == "SYMBOL"]
        has_user_file_anchor = any(anchor.type == "FILE_PATH" for anchor in user_anchors)
        if symbol_candidates:
            active_symbol = symbol_candidates[-1]
        elif has_user_file_anchor:
            active_symbol = None
        else:
            active_symbol = self.active_symbol
        raw_code_symbols = _extract_code_symbols(result.query_plan.raw)
        active_code_span_symbols = raw_code_symbols or list(self.active_code_span_symbols)
        path_scope = list(getattr(result.retrieval_spec.filters, "path_scope", []) or [])
        active_domains = list(result.retrieval_spec.domains or [])
        active_domain = active_domains[0] if len(active_domains) == 1 else self.active_domain
        return ConversationState(
            active_intent=result.intent,
            active_domain=active_domain,
            active_anchors=list(user_anchors),
            active_symbol=active_symbol,
            active_path_scope=path_scope or list(self.active_path_scope),
            active_code_span_symbols=active_code_span_symbols,
            last_query=result.query_plan.raw,
            turn_index=self.turn_index + 1,
        )


class RepoContext(BaseModel):
    model_config = ConfigDict(extra="forbid")

    languages: list[str] = Field(default_factory=list)
    available_domains: list[str] = Field(default_factory=lambda: ["CODE", "DOCS"])
    available_layers: list[str] = Field(default_factory=list)


class IntentDecision(BaseModel):
    model_config = ConfigDict(extra="forbid")

    intent: IntentType
    confidence: float = 0.0
    reason: str = ""

    @field_validator("confidence")
    @classmethod
    def clamp_confidence(cls, value: float) -> float:
        return max(0.0, min(1.0, float(value)))


def _extract_code_symbols(raw: str) -> list[str]:
    symbols: list[str] = []
    for match in _INLINE_CODE_RE.finditer(raw or ""):
        snippet = match.group(1)
        for token in _CODE_SYMBOL_RE.findall(snippet):
            if token not in symbols:
                symbols.append(token)
    return symbols[:8]