"""
FastAPI application exposing the OpenEnv-compatible HTTP API.
Endpoints: GET /health, GET /metadata, GET /schema,
           POST /reset, POST /step, POST /state, GET /docs
"""

from typing import Optional
from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
import uvicorn

from models import DataCleaningAction, DataCleaningObservation, DataCleaningState
from server.environment import DataCleaningEnvironment

app = FastAPI(
    title="Data Cleaning OpenEnv",
    description="A real-world data cleaning environment for AI agent training.",
    version="0.1.0",
)

# Single shared environment instance (stateful server)
env = DataCleaningEnvironment()


class ResetRequest(BaseModel):
    task_id: Optional[int] = None


class StepResponse(BaseModel):
    observation: DataCleaningObservation
    reward: float
    done: bool
    info: dict = {}


# ------------------------------------------------------------------
# Routes
# ------------------------------------------------------------------

@app.get("/health")
def health():
    return {"status": "healthy"}


@app.get("/metadata")
def metadata():
    return {
        "name": "data-cleaning-env",
        "description": (
            "A real-world data cleaning environment where an AI agent fixes "
            "missing values, duplicate rows, format inconsistencies, outliers, "
            "and dtype errors across three progressively harder tasks."
        ),
        "version": "0.1.0",
        "tags": ["openenv", "data-cleaning", "rl", "real-world"],
        "tasks": [
            {"id": "task1", "name": "Fill Missing Values", "difficulty": "easy"},
            {"id": "task2", "name": "Fix Formats and Remove Duplicates", "difficulty": "medium"},
            {"id": "task3", "name": "Full Cleaning Pipeline", "difficulty": "hard"},
        ],
    }


@app.get("/schema")
def schema():
    return {
        "action": {
            "type": "object",
            "properties": {
                "operation": {
                    "type": "string",
                    "enum": [
                        "fill_missing",
                        "drop_duplicates",
                        "fix_format",
                        "replace_value",
                        "drop_outliers",
                        "fix_dtype",
                    ],
                },
                "column": {"type": "string", "nullable": True},
                "params": {"type": "object", "nullable": True},
            },
            "required": ["operation"],
        },
        "observation": {
            "type": "object",
            "properties": {
                "done":             {"type": "boolean"},
                "reward":           {"type": "number"},
                "data_preview":     {"type": "string"},
                "data_shape":       {"type": "array", "items": {"type": "integer"}},
                "missing_counts":   {"type": "object"},
                "duplicate_count":  {"type": "integer"},
                "dtype_issues":     {"type": "object"},
                "task_description": {"type": "string"},
                "message":          {"type": "string"},
                "step_count":       {"type": "integer"},
                "current_score":    {"type": "number"},
            },
        },
        "state": {
            "type": "object",
            "properties": {
                "episode_id":       {"type": "string"},
                "task_id":          {"type": "integer"},
                "step_count":       {"type": "integer"},
                "max_steps":        {"type": "integer"},
                "total_errors":     {"type": "integer"},
                "errors_remaining": {"type": "integer"},
            },
        },
    }


@app.post("/reset", response_model=StepResponse)
def reset(req: ResetRequest = ResetRequest()):
    try:
        obs = env.reset(task_id=req.task_id)
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))
    return StepResponse(observation=obs, reward=0.0, done=False)


@app.post("/step", response_model=StepResponse)
def step(action: DataCleaningAction):
    try:
        obs = env.step(action)
    except RuntimeError as e:
        raise HTTPException(status_code=400, detail=str(e))
    return StepResponse(observation=obs, reward=obs.reward, done=obs.done)


@app.post("/state", response_model=DataCleaningState)
def state():
    return env.state()


# ------------------------------------------------------------------
# Entry point (required by openenv-core and [project.scripts])
# ------------------------------------------------------------------

def main():
    uvicorn.run("server.app:app", host="0.0.0.0", port=8000)


if __name__ == "__main__":
    main()