import os
import json
import subprocess
import ast

# Import strict prompts
from prompt import *

from langchain_openai import ChatOpenAI
from langchain_core.prompts import ChatPromptTemplate


def add_app_to_installed_apps(settings_path: str, app_name: str):
    with open(settings_path, "r", encoding="utf-8") as f:
        lines = f.readlines()

    in_installed_apps = False
    already_added = False
    new_lines = []

    for line in lines:
        if line.strip().startswith("INSTALLED_APPS"):
            in_installed_apps = True

        if in_installed_apps and f'"{app_name}"' in line:
            already_added = True

        if in_installed_apps and line.strip() == "]":
            if not already_added:
                new_lines.append(f'    "{app_name}",\n')
            in_installed_apps = False

        new_lines.append(line)

    if not already_added:
        with open(settings_path, "w", encoding="utf-8") as f:
            f.writelines(new_lines)


# ============================================================
# HELPER FUNCTIONS
# ============================================================

def run_cmd(command, cwd=None):
    """Runs terminal commands safely."""
    result = subprocess.run(
    command.split(),
    cwd=cwd,
    stdout=subprocess.PIPE,
    stderr=subprocess.PIPE,
    text=True
)

    
    if result.returncode != 0:
        print("❌ Command failed:", command)
        print(result.stderr)
        raise Exception(result.stderr)
    return result.stdout


def write_file(path, content):
    os.makedirs(os.path.dirname(path), exist_ok=True)
    with open(path, "w", encoding="utf8") as f:
        f.write(content)


def is_valid_python(code: str) -> bool:
    try:
        ast.parse(code)
        return True
    except:
        return False

# ===================README FILE GENERATOR ===================

def generate_readme_with_llm(spec_json, project_path, llm):
    chain = ChatPromptTemplate.from_messages([
        ("system", README_PROMPT),
        ("user", "{json_input}")
    ])

    runnable = chain | llm
    result = runnable.invoke({
        "json_input": json.dumps(spec_json, indent=2)
    })

    readme_content = result.content.strip()

    write_file(os.path.join(project_path, "README.md"), readme_content)
    print("📘 README.md generated successfully.")


# ============================================================
# CUSTOM FILE VALIDATORS
# ============================================================

def is_valid_serializer(code):
    """Rejects dynamic serializer patterns."""
    forbidden = ["globals(", "type(", "for ", "_create", "json_input"]
    if any(f in code for f in forbidden):
        return False
    if "class " not in code:
        return False
    if "Serializer" not in code:
        return False
    return is_valid_python(code)


def is_valid_views(code):
    """Reject dynamic views or helper functions."""
    forbidden = ["globals(", "type(", "_create", "for ", "json_input"]
    if any(f in code for f in forbidden):
        return False
    if "APIView" not in code:
        return False
    return is_valid_python(code)


def is_valid_urls(code):
    forbidden = ["globals(", "type(", "_create", "json_input"]
    if any(f in code for f in forbidden):
        return False
    
    if "urlpatterns" not in code:
        return False
    if "path(" not in code:
        return False
    if "<int:pk>" not in code:
        return False

    # No leading slash allowed
    if 'path("/' in code or "path('/" in code:
        return False

    return is_valid_python(code)


# ============================================================
# GENERATION LOGIC (AUTO-FIX)
# ============================================================

def generate_code_with_fix(
    prompt,
    json_slice,
    *,
    llm,
    validator=None,
    retries=5,
):

    for attempt in range(retries):
        print(f"🧠 Generating (attempt {attempt+1})...")

        chain = ChatPromptTemplate.from_messages([
            ("system", prompt),
            ("user", "{json_input}")
        ])

        runnable = chain | llm
        result = runnable.invoke({
            "json_input": json.dumps(json_slice, indent=2)
        })

        code = result.content.strip()


        # Use custom validator if provided
        if validator:
            if validator(code):
                print("✅ File valid.")
                return code
        else:
            # Syntax-only validation
            if is_valid_python(code):
                print("✅ File valid.")
                return code

        print("❌ Invalid file. Regenerating...")

    raise Exception("❌ Could not generate a valid file after retries.")


def generate_urls_with_fix(prompt, json_slice, *, llm, retries=5):
    return generate_code_with_fix(prompt, json_slice, validator=is_valid_urls,llm=llm, retries=retries)


# ============================================================
# MAIN PROJECT GENERATOR
# ============================================================

import os
import sys

def generate_full_project(spec_json, output_dir, llm, project_name):
    print("generating project")
    
    print("creating path")

    project_path = os.path.join(output_dir, project_name)
    os.makedirs(output_dir, exist_ok=True)

    PYTHON = sys.executable  # ✅ always correct python

    # -----------------------------
    # 1) CREATE DJANGO PROJECT
    # -----------------------------
    try:
        print("🚀 Creating Django project...")
        run_cmd(f"{PYTHON} -m django startproject {project_name}", cwd=output_dir)
    except Exception as e:
        raise RuntimeError(f"Failed to create Django project '{project_name}'") from e

    # -----------------------------
    # 2) CREATE APPS
    # -----------------------------
    try:
        for app in spec_json.get("apps", {}):
            print(f"📦 Creating app: {app}")
            run_cmd(f"{PYTHON} manage.py startapp {app}", cwd=project_path)

            settings_path = os.path.join(
                project_path,
                project_name,
                "settings.py"
            )

            add_app_to_installed_apps(settings_path, app)

    except Exception as e:
        raise RuntimeError("Failed while creating Django apps") from e

    # -----------------------------
    # 3) GENERATE FILES FOR EACH APP
    # -----------------------------
    for app_name, app_spec in spec_json.get("apps", {}).items():
        try:
            print(f"📝 Generating code for app: {app_name}")
            app_dir = os.path.join(project_path, app_name)

            if not os.path.exists(app_dir):
                raise FileNotFoundError(f"App directory not found: {app_dir}")

            models_slice = {"models": app_spec.get("models", {})}

            serializer_slice = {
                "model_names": sorted(app_spec.get("models", {}).keys())
            }
            admin_slice = {"model_names": list(app_spec.get("models", {}).keys())}

            views_slice = {
                "model_names": list(app_spec.get("models", {}).keys()),
                "apis": app_spec.get("apis", {})
            }

            urls_slice = {
                "model_names": list(app_spec.get("models", {}).keys()),
                "apis": app_spec.get("apis", {}),
                "base_url": spec_json.get("api_config", {}).get("base_url", "/api/")
            }

            models_code = generate_code_with_fix(
                MODELS_PROMPT, models_slice, validator=is_valid_python, llm=llm
            )
            write_file(os.path.join(app_dir, "models.py"), models_code)

            serializers_code = generate_code_with_fix(
                SERIALIZERS_PROMPT, serializer_slice, validator=is_valid_serializer, llm=llm
            )
            write_file(os.path.join(app_dir, "serializers.py"), serializers_code)

            views_code = generate_code_with_fix(
                VIEWS_PROMPT, views_slice, validator=is_valid_views, llm=llm
            )
            write_file(os.path.join(app_dir, "views.py"), views_code)

            urls_code = generate_urls_with_fix(
                URLS_PROMPT, urls_slice, llm=llm
            )
            write_file(os.path.join(app_dir, "urls.py"), urls_code)

            admin_code = generate_code_with_fix(
                ADMIN_PROMPT, admin_slice, validator=is_valid_python, llm=llm
            )
            write_file(os.path.join(app_dir, "admin.py"), admin_code)

        except Exception as e:
            raise RuntimeError(f"Code generation failed for app '{app_name}'") from e

    # -----------------------------
    # 4) GENERATE REQUIREMENTS
    # -----------------------------
    try:
        requirements_slice = {
            "auth": spec_json.get("auth", {}),
            "database": spec_json.get("database", {}),
            "deployment": spec_json.get("deployment", {})
        }

        requirements_code = generate_code_with_fix(
            REQUIREMENTS_PROMPT, requirements_slice, llm=llm
        )
        write_file(os.path.join(project_path, "requirements.txt"), requirements_code)

    except Exception as e:
        raise RuntimeError("Failed to generate requirements.txt") from e

    # -----------------------------
    # 5) PROJECT URLS
    # -----------------------------
    try:
        project_urls_slice = {
            "project_name": project_name,
            "apps": list(spec_json.get("apps", {}).keys()),
            "base_url": spec_json.get("api_config", {}).get("base_url", "/api/")
        }

        project_urls_code = generate_code_with_fix(
            PROJECT_URLS_PROMPT,
            project_urls_slice,
            validator=is_valid_python, llm=llm
        )

        write_file(
            os.path.join(project_path, project_name, "urls.py"),
            project_urls_code
        )

    except Exception as e:
        raise RuntimeError("Failed to generate project urls.py") from e

    # -----------------------------
    # 6) README (OPTIONAL)
    # -----------------------------
    try:
        generate_readme_with_llm(spec_json, project_path, llm=llm)
    except Exception as e:
        print("⚠ README generation failed (non-blocking):", e)

    print("\n🎉 DONE! Project created at:", project_path)
    return project_path

def load_json_spec(path="json_output/spec.json"):
    with open(path, "r", encoding="utf-8") as f:
        return json.load(f)


#=============================Prompt_With_Model_Specification================

def generate_django_model_prompt(project_name: str, description: str, llm):
    """
    Uses LLM to generate a high-quality, structured prompt
    for Django model development with clear specifications.
    """

    prompt = ChatPromptTemplate.from_messages([
    ("system", """
You are a senior Django backend architect with production experience.

Your task is to generate a SINGLE, CLEAN, PLAIN-TEXT PROMPT
that will later be used to generate Django models.py.

STRICT RULES:
- Output ONLY plain text.
- Do NOT use markdown, bullet points, headings, or code blocks.
- Do NOT include explanations or commentary.
- Do NOT generate Django code.
- Generate ONLY the final prompt text.

MODEL DESIGN RULES:
- Follow Django ORM best practices.
- Use deterministic, production-ready model structures.
- Infer missing models or fields if required to complete the system.
- Never invent unnecessary models.
- Every model MUST have a clear real-world purpose.

FIELD RULES:
- Infer sensible fields when the user does not specify all required fields.
- Use correct Django field types.
- Add timestamps (created_at, updated_at) when appropriate.
- Use UUID primary keys where suitable.
- Do NOT use dynamic patterns or metaprogramming.
- Ensure field names are snake_case.
- Ensure model names are PascalCase.

RELATIONSHIP RULES:
- Infer relationships only when logically required.
- Use ForeignKey for one-to-many relationships.
- Use OneToOneField only when explicitly required.
- Avoid ManyToMany unless clearly necessary.

META RULES:
- Include Meta options such as db_table and ordering.
- Include __str__ methods for all models.
- Ensure compatibility with Django REST Framework serializers and views.

OUTPUT QUALITY RULE:
The generated prompt must be precise, minimal, and implementation-ready,
so that another LLM can generate models.py without making assumptions.
"""),
    ("user", """
Project Name: {project_name}

User Requirements:
{description}

Generate a single, concise, implementation-ready PROMPT
that instructs an LLM to generate Django models.py.
""")
])


    chain = prompt | llm
    result = chain.invoke({
        "project_name": project_name,
        "description": description
    })

    return result.content.strip()