"""KB Accelerator AI conversion service.

Converts extracted KB article text into ResolutionFlow tree structures
using the Anthropic API (via the shared AI provider layer).
"""
import json
import logging
import re
import time
from typing import Any
from uuid import UUID

from sqlalchemy.ext.asyncio import AsyncSession

from app.core.ai_provider import get_ai_provider
from app.core.ai_quota_service import record_ai_usage, get_user_plan
from app.core.config import settings
from app.models.kb_import import KBImport, KBImportNode

logger = logging.getLogger(__name__)

# Cost estimation (Sonnet pricing)
COST_PER_INPUT_TOKEN = 3.0 / 1_000_000
COST_PER_OUTPUT_TOKEN = 15.0 / 1_000_000


from app.services.llm_utils import strip_markdown_fences as _strip_markdown_fences


def _try_repair_json(text: str) -> dict | None:
    """Attempt to repair common JSON issues from AI responses.

    Handles: trailing commas, unclosed brackets/braces, truncated responses.
    Returns parsed dict on success, None on failure.
    """
    # Strip trailing commas before closing brackets/braces
    repaired = re.sub(r",\s*([}\]])", r"\1", text)

    # Try parsing after comma cleanup
    try:
        return json.loads(repaired)
    except json.JSONDecodeError:
        pass

    # Try closing unclosed brackets/braces (truncated response)
    # Count open vs close brackets
    open_braces = repaired.count("{") - repaired.count("}")
    open_brackets = repaired.count("[") - repaired.count("]")

    if open_braces > 0 or open_brackets > 0:
        # Remove any trailing partial key-value pair or string
        # Find the last complete value (ends with }, ], ", number, true, false, null)
        truncated = repaired.rstrip()
        # Strip trailing partial string or key
        truncated = re.sub(r',\s*"[^"]*$', "", truncated)  # trailing "partial_key
        truncated = re.sub(r',\s*$', "", truncated)  # trailing comma

        # Close remaining brackets/braces
        truncated += "]" * max(0, open_brackets)
        truncated += "}" * max(0, open_braces)

        # Re-strip trailing commas that may have appeared
        truncated = re.sub(r",\s*([}\]])", r"\1", truncated)

        try:
            return json.loads(truncated)
        except json.JSONDecodeError:
            pass

    return None


def _estimate_cost(input_tokens: int, output_tokens: int) -> float:
    return (input_tokens * COST_PER_INPUT_TOKEN) + (output_tokens * COST_PER_OUTPUT_TOKEN)


# ── System Prompts ──

TROUBLESHOOTING_SYSTEM_PROMPT = """You are an MSP documentation specialist for ResolutionFlow. Your task is to convert a knowledge base article into an interactive troubleshooting decision tree.

Analyze the article and produce a JSON array of nodes that form a troubleshooting flow. Each node represents either a diagnostic question (decision point) or a resolution (solution).

## Node Types

- **question**: A diagnostic question with multiple answer options. Each option leads to another node.
- **resolution**: A terminal node with the solution/fix text.
- **action**: An instruction step that leads to the next node via next_node_id.
- **warning**: A caution or important note.

## Output Format

Return a JSON object with this structure:
```json
{
  "title": "Flow title derived from the article",
  "description": "Brief description of what this flow troubleshoots",
  "nodes": [
    {
      "id": "unique-node-id",
      "type": "question",
      "question": "What symptom is the user experiencing?",
      "options": [
        {"label": "Cannot connect", "next_node_id": "check-network"},
        {"label": "Slow performance", "next_node_id": "check-resources"}
      ],
      "confidence": 0.95,
      "source_excerpt": "The exact text from the article this node was derived from"
    },
    {
      "id": "check-network",
      "type": "action",
      "question": "Check the network connection and ping the server",
      "next_node_id": "network-result",
      "confidence": 0.88,
      "source_excerpt": "Step 1: Verify network connectivity..."
    },
    {
      "id": "solution-restart",
      "type": "resolution",
      "question": "Restart the service. The issue should now be resolved.",
      "confidence": 0.92,
      "source_excerpt": "Restarting the service resolves the connectivity issue."
    }
  ]
}
```

## Rules

1. Every node MUST have a unique `id` (descriptive kebab-case).
2. Every node MUST have a `confidence` score between 0.0 and 1.0.
3. Every node MUST have a `source_excerpt` — the exact text from the source article it was derived from.
4. The first node is the root of the decision tree.
5. All `next_node_id` and option `next_node_id` references must point to existing node IDs.
6. Detect implicit branching logic (e.g., "If X, do Y; otherwise Z") and create decision nodes.
7. Produce at least 3 nodes. Maximum 100 nodes.
8. Use high confidence (0.9+) for directly stated steps, medium (0.7-0.89) for reasonable inferences, low (<0.7) for significant interpretation.
9. Return ONLY valid JSON — no markdown fences, no explanation text."""

PROCEDURAL_SYSTEM_PROMPT = """You are an MSP documentation specialist for ResolutionFlow. Your task is to convert a knowledge base article into a procedural (step-by-step) flow.

Analyze the article and produce a JSON object with sequential steps and detected variables.

## Step Types

- **step**: A regular instruction step.
- **section_header**: A section divider/title (no action, just organizational).
- **warning**: A caution or important note that should be highlighted.

## Variable Detection

Identify values that would change between executions (server names, IPs, usernames, domains, etc.) and replace them with `[VAR:variable_name]` tokens. Also produce an intake_form that captures these variables before execution.

## Output Format

Return a JSON object with this SHAPE (DO NOT copy the placeholders below
verbatim — fill each field with content derived from the actual KB article
the engineer attached, NOT from this schema):
```json
{
  "title": "<procedure title derived from the article>",
  "description": "<brief description of what this procedure accomplishes>",
  "steps": [
    {
      "id": "<unique-kebab-case-id>",
      "type": "step|warning|section_header",
      "content": "<step body — may include [VAR:<your_variable>] interpolation>",
      "confidence": <float 0.0-1.0>,
      "source_excerpt": "<the verbatim sentence/phrase from the article that this step came from>"
    }
  ],
  "intake_form": [
    {
      "variable_name": "<snake_case_name fitting THIS procedure>",
      "label": "<Human Label>",
      "field_type": "text|password|select|textarea|number|boolean",
      "required": true|false,
      "display_order": <integer>
    }
  ]
}
```

## Variable Type Mapping

- IP addresses → field_type: "text", variable like `ip_address`
- Server/computer names → field_type: "text", variable like `server_name`
- Domain names → field_type: "text", variable like `domain_name`
- Usernames/email → field_type: "text", variable like `username`
- Port numbers → field_type: "number", variable like `port`

## Rules

1. Every step MUST have a unique `id` (descriptive kebab-case).
2. Every step MUST have a `confidence` score between 0.0 and 1.0.
3. Every step MUST have a `source_excerpt` — the exact text from the source article.
4. Preserve the original step ordering from the article.
5. Detect ALL instance-specific values and replace with `[VAR:name]` tokens.
6. Generate an intake_form entry for each unique variable detected.
7. Produce at least 2 steps. Maximum 100 steps.
8. Use high confidence (0.9+) for directly stated steps, medium (0.7-0.89) for inferences, low (<0.7) for significant interpretation.
9. Return ONLY valid JSON — no markdown fences, no explanation text."""


def _build_user_message(
    source_text: str,
    source_metadata: dict[str, Any] | None,
    source_filename: str | None,
) -> str:
    """Build the user message containing the extracted text and metadata."""
    parts = []

    if source_filename:
        parts.append(f"Source file: {source_filename}")

    if source_metadata:
        headings = source_metadata.get("headings", [])
        if headings:
            heading_text = ", ".join(
                f"H{h['level']}: {h['text']}" for h in headings[:20]
            )
            parts.append(f"Detected headings: {heading_text}")

        lists = source_metadata.get("lists", [])
        if lists:
            parts.append(f"Detected {len(lists)} list(s) in the document.")

        tables = source_metadata.get("tables", [])
        if tables:
            parts.append(f"Detected {len(tables)} table(s) in the document.")

    parts.append(f"\n--- ARTICLE CONTENT ---\n\n{source_text}")

    return "\n".join(parts)


def _parse_troubleshooting_response(
    data: dict[str, Any],
    kb_import_id: UUID,
) -> tuple[list[KBImportNode], str, str | None]:
    """Parse AI response into KBImportNode records for troubleshooting flows.

    Returns (nodes, title, description).
    """
    title = data.get("title", "Imported Troubleshooting Flow")
    description = data.get("description")
    raw_nodes = data.get("nodes", [])

    if not raw_nodes:
        raise ValueError("AI returned no nodes")

    # Build parent mapping from the tree structure
    # First node is root (no parent). For others, trace via options/next_node_id.
    node_id_to_parent: dict[str, str | None] = {}
    node_id_to_data: dict[str, dict[str, Any]] = {}
    for node in raw_nodes:
        nid = node.get("id", "")
        node_id_to_data[nid] = node
        if nid not in node_id_to_parent:
            node_id_to_parent[nid] = None  # default: no parent

    # Trace parent relationships (only set if it won't create a cycle)
    def _would_cycle(child: str, parent: str) -> bool:
        """Check if setting child's parent to parent creates a cycle."""
        visited: set[str] = set()
        cur: str | None = parent
        while cur:
            if cur == child:
                return True
            if cur in visited:
                break
            visited.add(cur)
            cur = node_id_to_parent.get(cur)
        return False

    for node in raw_nodes:
        nid = node.get("id", "")
        # Options point to children
        for opt in node.get("options", []):
            child_id = opt.get("next_node_id")
            if child_id and child_id in node_id_to_data and not _would_cycle(nid, child_id):
                node_id_to_parent[child_id] = nid
        # next_node_id points to child
        next_id = node.get("next_node_id")
        if next_id and next_id in node_id_to_data and not _would_cycle(nid, next_id):
            node_id_to_parent[next_id] = nid

    # Create import node records preserving order
    import uuid as uuid_mod
    node_id_map: dict[str, uuid_mod.UUID] = {}
    nodes: list[KBImportNode] = []

    for order, raw_node in enumerate(raw_nodes):
        node_uuid = uuid_mod.uuid4()
        nid = raw_node.get("id", f"node-{order}")
        node_id_map[nid] = node_uuid

    for order, raw_node in enumerate(raw_nodes):
        nid = raw_node.get("id", f"node-{order}")
        node_type = raw_node.get("type", "question")
        if node_type == "decision":
            node_type = "question"

        parent_str_id = node_id_to_parent.get(nid)
        parent_uuid = node_id_map.get(parent_str_id) if parent_str_id else None

        # Build content JSONB
        content: dict[str, Any] = {
            "original_id": nid,
            "question": raw_node.get("question", ""),
        }
        if raw_node.get("options"):
            content["options"] = raw_node["options"]
        if raw_node.get("next_node_id"):
            content["next_node_id"] = raw_node["next_node_id"]

        import_node = KBImportNode(
            id=node_id_map[nid],
            kb_import_id=kb_import_id,
            node_order=order,
            node_type=node_type,
            content=content,
            parent_node_id=parent_uuid,
            source_excerpt=raw_node.get("source_excerpt"),
            confidence_score=float(raw_node.get("confidence", 0.5)),
            user_edited=False,
            user_approved=False,
        )
        nodes.append(import_node)

    return nodes, title, description


def _parse_procedural_response(
    data: dict[str, Any],
    kb_import_id: UUID,
) -> tuple[list[KBImportNode], str, str | None, list[dict[str, Any]] | None]:
    """Parse AI response into KBImportNode records for procedural flows.

    Returns (nodes, title, description, intake_form).
    """
    title = data.get("title", "Imported Procedure")
    description = data.get("description")
    raw_steps = data.get("steps", [])
    intake_form = data.get("intake_form")

    if not raw_steps:
        raise ValueError("AI returned no steps")

    import uuid as uuid_mod
    nodes: list[KBImportNode] = []

    for order, raw_step in enumerate(raw_steps):
        content: dict[str, Any] = {
            "original_id": raw_step.get("id", f"step-{order}"),
            "content": raw_step.get("content", ""),
        }

        node_type = raw_step.get("type", "step")
        if node_type not in ("step", "section_header", "warning"):
            node_type = "step"

        import_node = KBImportNode(
            id=uuid_mod.uuid4(),
            kb_import_id=kb_import_id,
            node_order=order,
            node_type=node_type,
            content=content,
            parent_node_id=None,  # Procedural flows are linear
            source_excerpt=raw_step.get("source_excerpt"),
            confidence_score=float(raw_step.get("confidence", 0.5)),
            user_edited=False,
            user_approved=False,
        )
        nodes.append(import_node)

    return nodes, title, description, intake_form


async def convert_document(
    kb_import: KBImport,
    db: AsyncSession,
) -> list[KBImportNode]:
    """Run AI conversion on an extracted KB article.

    Creates KBImportNode records and updates the kb_import status.
    Returns the created nodes.
    """
    start_time = time.monotonic()

    # Select system prompt based on target type
    if kb_import.target_type == "troubleshooting":
        system_prompt = TROUBLESHOOTING_SYSTEM_PROMPT
    else:
        system_prompt = PROCEDURAL_SYSTEM_PROMPT

    user_message = _build_user_message(
        source_text=kb_import.source_text,
        source_metadata=kb_import.source_metadata,
        source_filename=kb_import.source_filename,
    )

    # Get AI provider with model routing
    model = settings.get_model_for_action("kb_convert")
    provider = get_ai_provider(model=model)

    try:
        raw_text, input_tokens, output_tokens = await provider.generate_json(
            system_prompt=[
                {"type": "text", "text": system_prompt},
                # cacheable: one of two stable constants (TROUBLESHOOTING_SYSTEM_PROMPT
                # or PROCEDURAL_SYSTEM_PROMPT) selected by target_type. Each
                # variant caches independently by text content.
            ],
            messages=[{"role": "user", "content": user_message}],
            max_tokens=16384,
        )
    except Exception as e:
        logger.error("AI conversion failed for kb_import=%s: %s", kb_import.id, e)
        kb_import.status = "failed"
        kb_import.error_message = f"AI processing error: {str(e)}"
        kb_import.processing_time_ms = int((time.monotonic() - start_time) * 1000)
        await db.flush()

        # Record failed usage
        plan = await get_user_plan(kb_import.account_id, db)
        await record_ai_usage(
            user_id=kb_import.created_by,
            account_id=kb_import.account_id,
            conversation_id=None,
            generation_type="kb_convert",
            tier=plan,
            input_tokens=0,
            output_tokens=0,
            estimated_cost=0.0,
            succeeded=False,
            counts_toward_quota=False,
            error_code="ai_error",
            extra_data={"kb_import_id": str(kb_import.id)},
            db=db,
        )
        return []

    # Parse JSON response
    raw_text = _strip_markdown_fences(raw_text)
    try:
        data = json.loads(raw_text)
    except json.JSONDecodeError as e:
        # Attempt JSON repair before giving up
        data = _try_repair_json(raw_text)
        if data is None:
            logger.error(
                "KB conversion JSON parse failed for kb_import=%s (%d chars). "
                "Parse error: %s. Raw response (first 2000 chars): %s",
                kb_import.id, len(raw_text), e, raw_text[:2000],
            )
            kb_import.status = "failed"
            kb_import.error_message = (
                "AI response could not be parsed as valid JSON. "
                "This can happen with very long articles — try again or simplify the article."
            )
            kb_import.processing_time_ms = int((time.monotonic() - start_time) * 1000)
            kb_import.ai_tokens_input = input_tokens
            kb_import.ai_tokens_output = output_tokens
            await db.flush()
            return []
        else:
            logger.info(
                "KB conversion JSON repaired for kb_import=%s (%d chars)",
                kb_import.id, len(raw_text),
            )

    # Parse into nodes based on target type
    try:
        intake_form = None
        if kb_import.target_type == "troubleshooting":
            nodes, title, description = _parse_troubleshooting_response(
                data, kb_import.id
            )
        else:
            nodes, title, description, intake_form = _parse_procedural_response(
                data, kb_import.id
            )
    except (ValueError, KeyError, TypeError) as e:
        logger.error("KB node parsing failed for kb_import=%s: %s", kb_import.id, e)
        kb_import.status = "failed"
        kb_import.error_message = f"Failed to parse AI response: {e}"
        kb_import.processing_time_ms = int((time.monotonic() - start_time) * 1000)
        kb_import.ai_tokens_input = input_tokens
        kb_import.ai_tokens_output = output_tokens
        await db.flush()
        return []

    # Persist nodes — insert roots first to satisfy parent_node_id FK,
    # then children in subsequent passes until all are inserted.
    remaining = list(nodes)
    inserted_ids: set[Any] = set()
    while remaining:
        batch = [
            n for n in remaining
            if n.parent_node_id is None or n.parent_node_id in inserted_ids
        ]
        if not batch:
            # Circular reference or orphan — force insert remaining to surface the real error
            for n in remaining:
                db.add(n)
            break
        for n in batch:
            db.add(n)
            inserted_ids.add(n.id)
        await db.flush()
        remaining = [n for n in remaining if n.id not in inserted_ids]

    # Update import record
    elapsed_ms = int((time.monotonic() - start_time) * 1000)
    confidence_scores = [n.confidence_score for n in nodes]
    avg_confidence = sum(confidence_scores) / len(confidence_scores) if confidence_scores else 0.0

    kb_import.status = "ready"
    kb_import.confidence_avg = avg_confidence
    kb_import.processing_time_ms = elapsed_ms
    kb_import.ai_tokens_input = input_tokens
    kb_import.ai_tokens_output = output_tokens

    # Store parsed metadata for commit phase
    if not kb_import.source_metadata:
        kb_import.source_metadata = {}
    kb_import.source_metadata["_conversion"] = {
        "title": title,
        "description": description,
        "node_count": len(nodes),
    }
    if intake_form:
        kb_import.source_metadata["_intake_form"] = intake_form

    await db.flush()

    # Record successful usage
    plan = await get_user_plan(kb_import.account_id, db)
    cost = _estimate_cost(input_tokens, output_tokens)
    await record_ai_usage(
        user_id=kb_import.created_by,
        account_id=kb_import.account_id,
        conversation_id=None,
        generation_type="kb_convert",
        tier=plan,
        input_tokens=input_tokens,
        output_tokens=output_tokens,
        estimated_cost=cost,
        succeeded=True,
        counts_toward_quota=True,
        error_code=None,
        extra_data={"kb_import_id": str(kb_import.id), "node_count": len(nodes)},
        db=db,
    )

    logger.info(
        "KB conversion complete: import=%s, nodes=%d, confidence=%.2f, time=%dms, tokens=%d/%d",
        kb_import.id, len(nodes), avg_confidence, elapsed_ms, input_tokens, output_tokens,
    )

    return nodes