"""Settings form for API keys and per-role model assignments.

The frontend uses the unified ModelCatalog (model_settings/catalog.yaml) so
users can mix-and-match providers per role. Models whose required env vars
aren't set are shown but greyed out based on the keys actually entered in the
form (not the process environment).
"""

import os

import streamlit as st

from scider.default.models import CAP_COMPLETION, ModelCatalog, ModelEntry

# Model roles grouped by category. experiment_coding is handled separately
# because it's tied to CODING_AGENT_VERSION.
MODEL_ROLE_GROUPS = {
    "Ideation": {
        "ideation": "Idea generation",
        "paper_search": "Paper search",
        "metric_search": "Metric search",
    },
    "Data Analysis": {
        "data": "Data analysis",
    },
    "Experiment": {
        "experiment": "Experiment agent",
    },
    "Critic": {
        "critic": "Critic evaluation",
    },
    "Paper Writing": {
        "writing": "Writing agent",
    },
    "System": {
        "history": "History compression",
    },
}

# Mapping: env var name -> (settings key, env var name)
_KEY_ENV_MAP = {
    "GEMINI_API_KEY": "gemini_api_key",
    "OPENAI_API_KEY": "openai_api_key",
    "ANTHROPIC_API_KEY": "anthropic_api_key",
}


def _initial_key_value(settings_key: str, current: dict) -> str:
    """Resolve initial key value from saved settings only (never from env)."""
    return current.get(settings_key, "")


def _entry_available_with_keys(entry: ModelEntry, provided_keys: dict[str, str]) -> bool:
    """Check if a model entry is available given the keys the user actually entered."""
    for env_var in entry.requires_env:
        settings_key = _KEY_ENV_MAP.get(env_var, "")
        if not provided_keys.get(settings_key, ""):
            return False
    return True


def _make_format_func(provided_keys: dict[str, str]):
    """Build a format_func that checks availability against provided keys, not os.environ."""

    def _format(model_id: str) -> str:
        entry = ModelCatalog.get(model_id)
        if entry is None:
            return f"{model_id} (unknown)"
        if not _entry_available_with_keys(entry, provided_keys):
            missing_env = [
                k for k in entry.requires_env if not provided_keys.get(_KEY_ENV_MAP.get(k, ""), "")
            ]
            missing_labels = ", ".join(missing_env)
            return f"{entry.id}  \u26a0 missing {missing_labels}"
        return f"{entry.id}  ({entry.provider})"

    return _format


def _completion_model_ids() -> list[str]:
    return [e.id for e in ModelCatalog.by_capability(CAP_COMPLETION)]


def _claude_completion_ids() -> list[str]:
    return [e.id for e in ModelCatalog.by_capability(CAP_COMPLETION) if e.provider == "anthropic"]


def _select_model(
    label: str,
    options: list[str],
    saved: str | None,
    fallback: str | None,
    key: str,
    format_func=None,
) -> str:
    default = saved if saved in options else (fallback if fallback in options else options[0])
    idx = options.index(default)
    kwargs = {}
    if format_func is not None:
        kwargs["format_func"] = format_func
    return st.selectbox(
        label,
        options,
        index=idx,
        key=key,
        **kwargs,
    )


def render_settings_form(current_settings: dict | None = None) -> dict | None:
    """Render settings form. Returns new settings dict on submit, None otherwise."""
    st.markdown("### Settings")
    st.caption(
        "Your settings are stored locally on this machine only and are never uploaded to the cloud."
    )

    # Make sure the catalog is loaded once before we render anything.
    ModelCatalog.load()

    current = current_settings or {}
    current_roles = current.get("model_roles", {})

    completion_ids = _completion_model_ids()
    claude_ids = _claude_completion_ids() or completion_ids

    # --- API Keys (outside form so we can read their values for rendering) ---
    # Streamlit forms capture widget values only on submit, so we use
    # session_state keys to read the *current* typed values for the
    # format_func, falling back to initial defaults.

    # Compute initial defaults: saved setting > env var > empty
    init_gemini = _initial_key_value("gemini_api_key", current)
    init_openai = _initial_key_value("openai_api_key", current)
    init_anthropic = _initial_key_value("anthropic_api_key", current)

    # Build a snapshot of provided keys for the format_func.
    # On first render we use initial values; after user types, session_state
    # updates on the next rerun (Streamlit forms only update on submit, but
    # since model dropdowns are inside the same form, the availability display
    # reflects the *initial* keys — which is correct: if you just opened
    # settings, the keys you already saved / have in env are "provided".)
    provided_keys = {
        "gemini_api_key": st.session_state.get("_sk_gemini", init_gemini),
        "openai_api_key": st.session_state.get("_sk_openai", init_openai),
        "anthropic_api_key": st.session_state.get("_sk_anthropic", init_anthropic),
    }

    format_func = _make_format_func(provided_keys)

    with st.form("settings_form"):
        # --- API Keys ---
        st.markdown("#### API Keys")
        st.caption(
            "Configure any combination of providers. Models whose key is missing "
            "will appear greyed-out in the dropdowns below."
        )

        gemini_api_key = st.text_input(
            "Gemini API Key",
            type="password",
            placeholder="Enter your Gemini API key",
            value=init_gemini,
            key="_sk_gemini",
        )
        openai_api_key = st.text_input(
            "OpenAI API Key",
            type="password",
            placeholder="Enter your OpenAI API key",
            value=init_openai,
            key="_sk_openai",
        )
        anthropic_api_key = st.text_input(
            "Anthropic (Claude) API Key",
            type="password",
            placeholder="Optional — needed for Claude coding agent",
            value=init_anthropic,
            key="_sk_anthropic",
        )

        st.divider()

        s2_api_key = st.text_input(
            "Semantic Scholar API Key",
            type="password",
            placeholder="Optional — enables Semantic Scholar paper search",
            value=_initial_key_value("s2_api_key", current),
        )
        st.caption(
            "Optional. If provided, paper search will also query Semantic Scholar "
            "in addition to arXiv. Get a key at https://www.semanticscholar.org/product/api"
        )

        # --- HuggingFace Dataset Download ---
        st.divider()
        st.markdown("#### HuggingFace Dataset Download")

        from scider.core import constant as _c

        if _c.HF_DATASET_DOWNLOAD_ENABLED:
            st.success(f"Enabled — max dataset size: {_c.HF_DATASET_MAX_SIZE_MB} MB")
        else:
            st.info("Disabled. Set `HF_DATASET_DOWNLOAD_ENABLED=true` in `.env` to enable.")
        st.caption(
            "When enabled, you can enter a HuggingFace dataset repo name "
            "(e.g. `google/fleurs`) instead of uploading a local file."
        )

        # --- Memory ---
        st.divider()
        st.markdown("#### Memory")
        mem_read = os.getenv("SCIDER_MEMORY_READ", "true").lower() in {"1", "true", "yes", "y"}
        mem_write = os.getenv("SCIDER_MEMORY_WRITE", "true").lower() in {"1", "true", "yes", "y"}
        if mem_read and mem_write:
            st.success("Reading and writing enabled")
        elif mem_read:
            st.info("Reading enabled, writing disabled")
        elif mem_write:
            st.info("Writing enabled, reading disabled")
        else:
            st.warning("Memory disabled")
        st.caption("Configure via `SCIDER_MEMORY_READ` / `SCIDER_MEMORY_WRITE` in `.env`.")

        # --- Coding Agent ---
        st.divider()
        st.markdown("#### Coding Agent")

        coding_version = os.getenv("CODING_AGENT_VERSION", "claude_sdk")
        if coding_version in ("v3", "claude_sdk"):
            version_label = "Claude Agent SDK"
        elif coding_version in ("v2", "openhands"):
            version_label = "OpenHands"
        elif coding_version == "native":
            version_label = "Native (SciDER)"
        else:
            version_label = coding_version
        st.text_input(
            "Coding Agent Backend",
            value=version_label,
            disabled=True,
            key="coding_agent_version_display",
        )
        st.caption(
            "To change the coding agent backend, set the `CODING_AGENT_VERSION` "
            "environment variable (`claude_sdk`, `openhands`, or `native`) in `.env`."
        )

        if coding_version in ("v3", "claude_sdk"):
            coding_options = claude_ids
            coding_fallback = "claude-haiku-4-5"
        else:
            coding_options = completion_ids
            coding_fallback = "gemini-2.5-pro"

        coding_model = _select_model(
            "Code generation model",
            coding_options,
            saved=current_roles.get("experiment_coding"),
            fallback=coding_fallback,
            key="model_role_experiment_coding",
            format_func=format_func,
        )

        # --- Per-role model selection ---
        st.divider()
        st.markdown("#### Model Assignments")
        st.caption(
            "Choose which model to use for each agent role. Models from any provider "
            "can be mixed freely."
        )

        role_selections: dict[str, str] = {}
        max_cols = 3
        for group_name, roles in MODEL_ROLE_GROUPS.items():
            st.markdown(f"**{group_name}**")
            role_items = list(roles.items())
            for row_start in range(0, len(role_items), max_cols):
                row = role_items[row_start : row_start + max_cols]
                cols = st.columns(max_cols)
                for col, (role, label) in zip(cols, row):
                    with col:
                        role_selections[role] = _select_model(
                            label,
                            completion_ids,
                            saved=current_roles.get(role),
                            fallback=None,
                            key=f"model_role_{role}",
                            format_func=format_func,
                        )

        role_selections["experiment_coding"] = coding_model

        # --- Submit ---
        submitted = st.form_submit_button("Save Settings", type="primary")

        if submitted:
            final_gemini = gemini_api_key.strip()
            final_openai = openai_api_key.strip()
            final_anthropic = anthropic_api_key.strip()
            final_s2 = s2_api_key.strip()

            if not (final_gemini or final_openai or final_anthropic):
                st.error("Provide at least one provider API key (Gemini, OpenAI, or Anthropic).")
                return None

            # Build final provided keys for availability check.
            final_keys = {
                "gemini_api_key": final_gemini,
                "openai_api_key": final_openai,
                "anthropic_api_key": final_anthropic,
            }

            # Validate that selected models have their keys filled in.
            unavailable = []
            for role, mid in role_selections.items():
                entry = ModelCatalog.get(mid)
                if entry and not _entry_available_with_keys(entry, final_keys):
                    missing_env = [
                        k
                        for k in entry.requires_env
                        if not final_keys.get(_KEY_ENV_MAP.get(k, ""), "")
                    ]
                    unavailable.append((role, mid, missing_env))

            if unavailable:
                lines = "\n".join(
                    f"- **{role}** \u2192 `{mid}` (missing: {', '.join(missing)})"
                    for role, mid, missing in unavailable
                )
                st.error("Some selected models are still missing API keys:\n" + lines)
                return None

            return {
                "gemini_api_key": final_gemini,
                "openai_api_key": final_openai,
                "anthropic_api_key": final_anthropic,
                "s2_api_key": final_s2,
                "model_roles": role_selections,
            }

    return None