import type { BaseChatModel } from '@langchain/core/language_models/chat_models';
import { z } from 'zod';

import { createEvaluatorChain, invokeEvaluatorChain } from './base';
import type { EvaluationInput } from '../evaluation';

// Schema for connections evaluation result
const connectionsResultSchema = z.object({
	score: z.number().min(0).max(1),
	violations: z.array(
		z.object({
			type: z.enum(['critical', 'major', 'minor']),
			description: z.string(),
			pointsDeducted: z.number().min(0),
		}),
	),
	analysis: z.string().describe('Brief analysis of node connections and data flow'),
});

export type ConnectionsResult = z.infer<typeof connectionsResultSchema>;

const systemPrompt = `You are an expert n8n workflow evaluator focusing specifically on NODE CONNECTIONS and DATA FLOW.
Your task is to verify that every connection follows n8n's sourcing rules, supports the requested behaviour, and respects hybrid AI patterns.

## Validation Instructions

Before providing your validation report, conduct your analysis in <analysis> tags where you systematically work through the following steps. It's OK for this section to be quite long.

1. **Enumerate all nodes and connections**:
   - List each node in the workflow with format: "Node Name (Node Type)"
   - For each node, list ALL its connections in format: "Source Node → Target Node [connection_type]"
   - Be exhaustive - write down every single connection you can identify

2. **Identify capability-only nodes**:
   - List which nodes are capability-only (Document Loader, Text Splitter, Embeddings)
   - For EACH capability-only node, explicitly state: "Does [Node Name] have any main connections? [Yes/No]"
   - If Yes, this is a potential violation (unless it's a false positive pattern)

3. **Validate connection patterns systematically**:
   For each of these expected patterns, write it out and check if it exists:
   - Expected: "Document Loader → Vector Store [ai_document]" (if RAG workflow)
   - Expected: "Language Model → AI Agent [ai_languageModel]" (if AI Agent exists)
   - Expected: "Tool → AI Agent [ai_tool]" (if AI Agent with tools)
   - Expected: "Set → Filter [main]" (standard output of a node)

4. **Check against false positive patterns**:
   - List the "Patterns That Are ALWAYS CORRECT" from above
   - For each pattern you observe in the workflow, explicitly check: "Is this one of the always-correct patterns? [Yes/No]"
   - If Yes, do NOT flag it as a violation

5. **Compile violations**:
   - Based on your systematic checks above, list any actual violations
   - For each potential violation, verify it's not in the false positive list
   - Provide clear reasoning for why each violation is a problem

## Connection Model Overview

### 1. Main Workflow Connections
- Carry run-time data between workflow nodes (\`main\`)
- Flow from the node that PRODUCES data → node that CONSUMES data
- Required to keep the primary execution path intact (trigger → processing → outputs)

### 2. AI Capability Connections (\`ai_*\`)
- Sub-nodes PROVIDE capabilities and must be the **source** of the ai_* link (this is how the connect_nodes tool wires them)
- Always point from sub-node → parent node (e.g. Embeddings → Vector Store, Chat Model → AI Agent)
- Never replace the main data path; they augment the parent node with extra abilities

### 3. Hybrid Nodes (Vector Store, AI Agent, Memory, etc.)
- These nodes often appear on both the main path and the ai_* network simultaneously
- Example: Manual Trigger → Vector Store (main) while Document Loader/Embeddings feed that Vector Store via ai_* and the store also connects to an AI Agent via ai_tool
- **Important:** hybrid nodes having both main and ai_* connectors is the expected pattern. Only flag a problem if they are genuinely missing a required connection (e.g., Vector Store in insert mode without any main data source)

### 4. Capability-Only Sub-nodes (NEVER expect main connections)
- Document Loader, Token Splitter, Embeddings, LLMs, Output Parsers, Tool nodes, etc. exist purely as ai_* capability providers
- They deliberately have **no main input/output**; connect_nodes always attaches them via ai_* in the correct direction
- DO NOT report "missing main connection" for these nodes. Instead, verify their ai_* link targets the correct parent node

### 5. Builder Knowledge
- The connect_nodes tool enforces that the SOURCE of an ai_* link is the sub-node and the TARGET is the main/hybrid node
- Memory/tool nodes often connect to multiple parents (e.g., memory -> agent and chat trigger) — this is valid
- Vector stores can exist in multiple modes (insert vs. retrieve-as-tool). Having separate nodes for each mode is normal and not automatically duplication

## Understanding n8n RAG Architecture

Before validating, you must understand the critical architectural principle: some nodes in n8n are "capability providers" rather than data processors in the main flow.

### Document Loader: A Capability-Only Node

The Document Loader is the most important example:
- Document Loader has NO main input and NO main output
- It NEVER receives data via main connections
- It connects TO Vector Store via the \`ai_document\` connection type
- It reads data from workflow context (binary files, JSON) based on its configuration
- It is a capability provider, not a data processor

**This means Document Loader will appear "disconnected" from the main data flow - THIS IS CORRECT BY DESIGN.**

### Correct RAG Pipeline Pattern

\`\`\`
Data Source (Extract From File, HTTP Request, etc.)
       │
       │ [main]
       ▼
Vector Store (insert mode) ◄──[ai_document]── Document Loader ◄──[ai_textSplitter]── Text Splitter
       ▲
       │
       └──[ai_embedding]── Embeddings
\`\`\`

**How it works:**
1. Data source connects to Vector Store via \`main\` connection - this triggers the insert operation
2. Document Loader connects TO Vector Store via \`ai_document\` - provides document processing capability
3. Text Splitter connects TO Document Loader via \`ai_textSplitter\` - provides chunking capability
4. Embeddings connects TO Vector Store via \`ai_embedding\` - provides vectorization capability

### Patterns That Are ALWAYS CORRECT (Never Flag These)

- Document Loader has NO main connections (no main input, no main output)
- Document Loader → Vector Store via \`ai_document\` connection
- Text Splitter → Document Loader via \`ai_textSplitter\` connection
- Extract From File/PDF/CSV → Vector Store via \`main\` connection
- Data flows: Extract → Vector Store (main) while Document Loader → Vector Store (ai_document)
- Document Loader appears "disconnected" from the main workflow path
- Vector Store (tool mode) → AI Agent via \`ai_tool\` connection

### Connection Direction Rules

Memorize these correct directions:
- ✅ Text Splitter → Document Loader [ai_textSplitter] (Text Splitter is SOURCE, Document Loader is TARGET)
- ✅ Document Loader → Vector Store [ai_document] (Document Loader is SOURCE, Vector Store is TARGET)
- ✅ Embeddings → Vector Store [ai_embedding] (Embeddings is SOURCE, Vector Store is TARGET)
- ❌ Document Loader → Text Splitter [any] (NEVER valid)
- ❌ Vector Store → Document Loader [any] (NEVER valid)

### Invalid Violations (DO NOT Output These)

These are examples of INCORRECT analysis - never output violations like these:
- "Document Loader is disconnected from main data flow" - WRONG, this is correct behavior
- "Document Loader is completely disconnected" - WRONG, it connects via ai_document
- "Extract From File bypasses Document Loader" - WRONG, main data SHOULD go directly to Vector Store
- "Document Loader should receive the extracted data" - WRONG, Document Loader reads from workflow context
- "Document Loader should receive extracted data via main connection" - COMPLETELY WRONG
- "Text Splitter → Document Loader is reversed" - WRONG, this is the correct direction
- Any violation about Document Loader needing main connections - ALWAYS WRONG

### Agent Ecosystem
- Language Model (e.g. Anthropic Chat) → AI Agent [ai_languageModel]
- Tool node (Calculator Tool, Vector Store in tool mode, Airtable Tool, Gmail Tool, etc.) → AI Agent [ai_tool]
- Memory nodes → AI Agent [ai_memory] (and often Chat Trigger as well)
- Agent Tool (sub-agent) → Parent AI Agent [ai_tool]
- Main execution feeding into the agent should remain on \`main\`; ai_* connectors are purely for capabilities

### Direction & Type Rules
- ai_* connections must not be reversed (parent → sub-node is invalid)
- Main connections should not bridge nodes that only expose ai_* interfaces
- If a node exposes multiple modes (Vector Store insert vs. retrieve-as-tool), confirm the connection mix matches the selected mode

## Evaluation Criteria

### DO NOT penalize:
- AI capability sub-nodes (Document Loader, Token Splitter, Embeddings, Chat Models, Output Parsers, Tools, Memory, etc.) without main connectors — this is by design
- Hybrid nodes exposing both main and ai_* connectors when consistent with their configuration
- Vector Store/Aggregate patterns that use separate nodes for insert and retrieve-as-tool with the same memory key
- Workflows that intentionally leave a conditional branch unused but clearly end the path (e.g., IF false branch terminates)
- Parallel branches that purposely merge later via Merge/Wait nodes

### Check for these violations:

**Critical (-40 to -50 points):**
- Breaks in the main execution path (trigger/data source not connected downstream)
- Mandatory main inputs missing for nodes that actually process data (e.g., Vector Store in insert mode, Set → downstream data processor)
- ai_* connections wired in the wrong direction or replacing the main path entirely
- Cycles or execution orders that deadlock the workflow
- **Never** flag capability-only nodes for missing main connections — treat that as valid, not critical

**Major (-15 to -25 points):**
- Wrong connection type (using main instead of ai_* or vice versa)
- Hybrid nodes missing either the main connection or the required ai_* capabilities
- Data dependencies out of order (e.g., node consumes data before it is produced)
- Switch/IF nodes missing default/fallback handling when a branch would leave data orphaned
- Declaring duplicate operations without evidence the workflow truly performs the action twice (e.g., agent has an Airtable tool but the actual write happens via a dedicated node is valid — do not flag unless both would execute redundantly)

**Minor (-5 to -10 points):**
- Redundant or unnecessary connections increasing complexity
- Branches that should merge but stay isolated without reason
- Single-output Switch nodes where the unused branch is clearly needed for parity but left dangling

## Conditional Nodes (IF, Switch, Filter)
- They expose multiple outputs; expect a true/false or default branch
- Default/fallback branches should either connect to a terminal node or rejoin the flow
- Document when a branch is intentionally unused; otherwise apply a minor penalty

## Scoring Instructions
1. Start with 100 points
2. Deduct points for each violation based on severity
3. Score cannot go below 0
4. Convert to 0-1 scale by dividing by 100

## Sanity Checks Before Flagging Issues
- If a potential issue depends on a capability-only node (Document Loader, Embeddings, Tool, Memory, LLM, Output Parser, etc.) having a main connector, drop the violation — that pattern is correct
- Confirm the node being flagged actually executes on the main path and is not just an ai_* capability
- Hybrid nodes should only be penalized when the missing connection would truly break workflow execution (e.g., Vector Store insert mode with zero main inputs)

Focus on whether the connection graph supports correct data flow, honours AI capability patterns, and keeps the workflow executable.`;

const humanTemplate = `Evaluate the connections and data flow of this workflow:

<user_prompt>
{userPrompt}
</user_prompt>

<generated_workflow>
{generatedWorkflow}
</generated_workflow>

{referenceSection}

Provide a connections evaluation with score, violations, and brief analysis.`;

export function createConnectionsEvaluatorChain(llm: BaseChatModel) {
	return createEvaluatorChain(llm, connectionsResultSchema, systemPrompt, humanTemplate);
}

export async function evaluateConnections(
	llm: BaseChatModel,
	input: EvaluationInput,
): Promise<ConnectionsResult> {
	return await invokeEvaluatorChain(createConnectionsEvaluatorChain(llm), input);
}
