import os
import uuid
import pygit2
from pygit2.enums import BranchType

from sqlalchemy import select, delete, bindparam
from sqlalchemy.orm import Session
from sqlalchemy.dialects.postgresql import insert
from sqlalchemy.sql.operators import in_op, and_
from starlette.exceptions import HTTPException
from starlette.requests import Request
from fastapi import APIRouter
from starlette.responses import JSONResponse

from pillar_tool.db import Host, StateAssignment
from pillar_tool.db.models.top_data import Environment, EnvironmentAssignment, State
from pillar_tool.util.files import recursive_list_dir
from pillar_tool.util.validation import validate_environment_name
from pillar_tool.util import config, Config
from pillar_tool.git.repository import checkout_remote_branch

router = APIRouter(
    prefix="/environment",
    tags=["environment"],
)


@router.get("")
def environments_get(req: Request):
    """
    Retrieve all environments.

    Fetches and returns a list of environment names from the database.

    Returns:
        JSONResponse: A JSON response with status code 200 containing a list of environment names (strings).
    """
    db: Session = req.state.db

    print("[DEBUG] environments_get: retrieving all environments")
    result = db.execute(select(Environment)).fetchall()
    environments: list[Environment] = list(map(lambda x: x[0], result))

    print("[DEBUG] environments_get: found {} environment(s) in database".format(len(environments)))

    return JSONResponse(status_code=200, content=[env.name for env in environments])


@router.get("/{name}")
def environment_get(req: Request, name: str):
    """
    Retrieve a specific environment by name.

    Fetches and returns details of the specified environment.
    Returns 404 if no such environment exists.

    Args:
        req (Request): The incoming request object.
        name (str): The name of the environment to retrieve.

    Returns:
        JSONResponse: A JSON response with status code 200 and the environment details on success,
                      or 404 if not found.
    """
    db: Session = req.state.db

    print("[DEBUG] environment_get: retrieving environment '{}'".format(name))

    # Validate name before query
    if not validate_environment_name(name):
        print("[DEBUG] environment_get: ERROR - Invalid environment name '{}'. Environment names must use only alphanumeric, underscore or dash characters.".format(name))
        raise HTTPException(status_code=400, detail="Invalid environment name format")

    stmt = select(Environment).where(Environment.name == name)
    result = db.execute(stmt).fetchall()

    if len(result) == 0:
        print("[DEBUG] environment_get: ERROR - No environment found with name '{}'".format(name))
        raise HTTPException(status_code=404, detail="No such environment exists")

    assert len(result) == 1

    env: Environment = result[0][0]
    print("[DEBUG] environment_get: resolved environment '{}' with id={}".format(env.name, env.id))

    # Get assigned hosts count as an example of additional info
    hosts_stmt = select(Host).join(EnvironmentAssignment, Host.id == EnvironmentAssignment.host_id)\
                              .where(EnvironmentAssignment.environment_id == env.id)
    hosts_count = db.execute(hosts_stmt).fetchall().__len__()
    print("[DEBUG] environment_get: environment '{}' has {} host(s) assigned".format(env.name, hosts_count))

    return JSONResponse(status_code=200, content={
        'environment': env.name,
        'host_count': hosts_count
    })


@router.post("/{name}")
def environment_create(req: Request, name: str):
    """
    Create a new environment.

    Creates a new environment record in the database with the provided parameters.

    Args:
        req (Request): The incoming request object.
        name (str): The name of the environment (must be unique).

    Returns:
        JSONResponse: A JSON response with status code 201 on success,
                      or appropriate error codes (e.g., 409 if already exists, 400 for invalid format).
    """
    db = req.state.db

    print("[DEBUG] environment_create: creating new environment '{}'".format(name))

    # Validate name format
    if not validate_environment_name(name):
        print("[DEBUG] environment_create: ERROR - Invalid environment name '{}'. Environment names must use only alphanumeric, underscore or dash characters.".format(name))
        raise HTTPException(status_code=400,
                            detail="Invalid environment name. Use only alphanumeric, underscore or dash characters.")

    # Check if environment already exists
    stmt_check = select(Environment).where(Environment.name == name)
    existing = db.execute(stmt_check).fetchall()

    if len(existing) > 0:
        print("[DEBUG] environment_create: ERROR - Environment '{}' already exists in database. Duplicate environment creation rejected.".format(name))
        raise HTTPException(status_code=409, detail="Environment already exists")

    new_id = uuid.uuid4()
    db.execute(insert(Environment).values(id=new_id, name=name))
    print("[DEBUG] environment_create: created environment '{}' with id={}".format(name, new_id))

    return JSONResponse(status_code=201, content={
        'id': str(new_id),
        'name': name
    })


@router.delete("/{name}")
def environment_delete(req: Request, name: str):
    """
    Delete an environment by name.

    Deletes the specified environment from the database.
    Returns 409 if hosts are still assigned to this environment.
    Returns 404 if no such environment exists.

    Args:
        req (Request): The incoming request object.
        name (str): The name of the environment to delete.

    Returns:
        JSONResponse: A JSON response with status code 204 on successful deletion,
                      or appropriate error codes for conflicts or not found.
    """
    db = req.state.db

    print("[DEBUG] environment_delete: deleting environment '{}'".format(name))

    # Validate name format
    if not validate_environment_name(name):
        print("[DEBUG] environment_delete: ERROR - Invalid environment name '{}'. Environment names must use only alphanumeric, underscore or dash characters.".format(name))
        raise HTTPException(status_code=400, detail="Invalid environment name format")

    stmt = select(Environment).where(Environment.name == name)
    result = db.execute(stmt).fetchall()

    if len(result) == 0:
        print("[DEBUG] environment_delete: ERROR - No environment found with name '{}'".format(name))
        raise HTTPException(status_code=404, detail="No such environment exists")

    assert len(result) == 1

    env: Environment = result[0][0]
    print("[DEBUG] environment_delete: resolved environment '{}' with id={}".format(env.name, env.id))

    # Check for assigned hosts before deleting
    assignments_stmt = select(EnvironmentAssignment).where(
        EnvironmentAssignment.environment_id == env.id
    )
    assignments = db.execute(assignments_stmt).fetchall()

    if len(assignments) > 0:
        host_ids_stmt = select(EnvironmentAssignment.host_id).where(
            EnvironmentAssignment.environment_id == env.id
        )
        host_ids = [row[0] for row in db.execute(host_ids_stmt).fetchall()]

        # Get host names (could optimize this)
        hosts_stmt = select(Host).where(Host.id.in_(host_ids))
        hosts: list[Host] = list(map(lambda x: x[0], db.execute(hosts_stmt).fetchall()))

        print("[DEBUG] environment_delete: ERROR - Cannot delete environment '{}' because it has {} host(s) assigned: {}. All hosts must be unassigned before deletion.".format(name, len(assignments), [h.name for h in hosts]))
        return JSONResponse(status_code=409, content={
            'message': "Cannot delete an environment that still has hosts assigned",
            'assigned_hosts': [h.name for h in hosts]
        })

    # Delete the environment
    db.execute(delete(Environment).where(Environment.id == env.id))
    print("[DEBUG] environment_delete: successfully deleted environment '{}' (id={})".format(env.name, env.id))

    return JSONResponse(status_code=204, content={})

@router.patch("/{name}")
def environment_patch(req: Request, name: str) -> JSONResponse:

    db: Session = req.state.db
    cfg: Config = config()

    print("[DEBUG] environment_patch: importing/syncing environment '{}' from git".format(name))

    # Attempt to check the requested branch out
    try:
        checkout_remote_branch(cfg, name)
        print("[DEBUG] environment_patch: successfully checked out git branch '{}'".format(name))

        # create the environment if it did not exist already
        select_env_res = db.execute(select(Environment).where(Environment.name == name)).fetchall()
        if len(select_env_res) == 0:
            insert_env_res = db.execute(insert(Environment).values(id=uuid.uuid4(), name=name).returning(Environment)).fetchall()
            print("[DEBUG] environment_patch: environment '{}' does not exist in database, creating new record".format(name))
            if len(insert_env_res) == 0:
                print("[DEBUG] environment_patch: ERROR - Failed to create environment '{}' in database after git checkout. Database insert returned no results.".format(name))
                raise HTTPException(status_code=404, detail=f"Failed to create non-existent environment '{name}'")
            else:
                env: Environment = insert_env_res[0][0]
        else:
            env: Environment = select_env_res[0][0]
            print("[DEBUG] environment_patch: environment '{}' already exists in database (id={})".format(name, env.id))

        # Branch has been checked out
        all_files = recursive_list_dir(cfg.git.state_repo_path)
        sls_files = filter(lambda f: f.endswith(".sls"), all_files)
        state_file_paths = map(lambda x: x.replace("/init.sls", "").replace(".sls", ""), sls_files)
        state_names = list(map(lambda x: x.replace(f"{cfg.git.state_repo_path}/", "").replace("/", "."), state_file_paths))

        print("[DEBUG] environment_patch: found {} .sls file(s) in git repo '{}', resolving to {} state name(s)".format(len(all_files), cfg.git.state_repo_path, len(state_names)))

        # get all the existing states and the to be created ones
        select_res = db.execute(select(State).where(State.name.in_(state_names))).fetchall()
        states_known = {}
        for row in select_res:
            state: State = row[0]
            states_known[state.name] = state

        print("[DEBUG] environment_patch: {} of {} states already exist in database".format(len(states_known), len(state_names)))

        states_new = {
            state_name: State(name=state_name, id=uuid.uuid4()) for state_name in state_names if state_name not in states_known
        }

        print("[DEBUG] environment_patch: {} new state(s) to be created".format(len(states_new)))

        states =  {}
        states.update(states_known)
        states.update(states_new)

        # insert all states that don't exist already
        insert_stmt = insert(State)
        insert_assignment_stmt = insert(StateAssignment)
        for state in states_new.values():
            db.execute(insert_stmt.values(id=state.id, name=state.name))


        # ensure that all the state assignments exist
        state_ids = list(map(lambda x: x.id, states.values()))
        state_assignments_known = [
            x[0].state_id
            for x in db.execute(select(StateAssignment).where(StateAssignment.environment_id == env.id)).fetchall()
        ]
        print("[DEBUG] environment_patch: {} existing state assignment(s) found for environment '{}'".format(len(state_assignments_known), name))

        state_assignments_new = [
            state_id
            for state_id in map(lambda x: x.id, states.values()) if state_id not in state_assignments_known
        ]
        print("[DEBUG] environment_patch: {} new state assignment(s) to be created".format(len(state_assignments_new)))

        state_assignments_to_delete = [
            sid
            for sid in filter(lambda x: x not in state_ids, state_assignments_known)
        ]
        if len(state_assignments_to_delete) > 0:
            print("[DEBUG] environment_patch: {} stale state assignment(s) to be removed (states no longer exist in git)".format(len(state_assignments_to_delete)))

        for sid in state_assignments_to_delete:
            db.execute(delete(StateAssignment).where(and_(StateAssignment.state_id == sid, StateAssignment.environment_id == env.id))) # type: ignore

        insert_stmt = insert(StateAssignment)
        for sid in state_assignments_new:
            db.execute(insert_stmt.values(state_id=sid, environment_id=env.id))
        
        return JSONResponse(status_code=200, content={'message': "done"})


    except Exception as exc:
        print("[DEBUG] environment_patch: ERROR - Failed to import environment '{}': {}".format(name, str(exc)))
        raise HTTPException(status_code=404, detail=str(exc))