"""Source-specific collectors that read files and produce NormalizedMessages."""

from __future__ import annotations

import hashlib
import json
import logging
from dataclasses import dataclass
from typing import Any

from qc_trace.daemon.state import FileState
from qc_trace.daemon.watcher import ChangedFile
from qc_trace.schemas.claude_code.transform import transform_claude_v1
from qc_trace.schemas.codex_cli.transform import (
    CodexTransformContext,
    transform_codex_v1,
)
from qc_trace.schemas.cursor.transform import transform_cursor_v1
from qc_trace.schemas.gemini_cli.transform import transform_gemini_v1
from qc_trace.schemas.unified import NormalizedMessage, SessionContext
from qc_trace.utils.cursor_parser import parse_agent_transcript
from qc_trace.utils.repo_resolver import (
    decode_cursor_slug,
    extract_cursor_slug_from_path,
    extract_gemini_hash_from_path,
    resolve_repo,
)

logger = logging.getLogger("quickcall.collector")

# Cache CodexTransformContext per file path to avoid replaying from line 0
# on every poll cycle. Stores (last_line_processed, context) tuples.
_codex_context_cache: dict[str, tuple[int, CodexTransformContext]] = {}


@dataclass
class CollectResult:
    """Result from collecting a file."""

    messages: list[NormalizedMessage]
    new_state: FileState


def collect_file(
    changed: ChangedFile,
    existing_state: FileState | None,
    device_name: str | None = None,
    device_id: str | None = None,
    global_email: str | None = None,
    global_name: str | None = None,
    org: str | None = None,
) -> CollectResult:
    """Collect new messages from a changed file using the appropriate strategy."""
    collectors = {
        "claude_code": _collect_claude,
        "codex_cli": _collect_codex,
        "gemini_cli": _collect_gemini,
        "cursor": _collect_cursor,
    }
    collector_fn = collectors[changed.source]
    return collector_fn(changed, existing_state, device_name, device_id, global_email, global_name, org)


def _attach_context(messages: list[NormalizedMessage], ctx: SessionContext) -> None:
    """Attach a SessionContext to all messages in-place."""
    for msg in messages:
        msg.session_context = ctx


def _collect_claude(
    changed: ChangedFile,
    existing_state: FileState | None,
    device_name: str | None = None,
    device_id: str | None = None,
    global_email: str | None = None,
    global_name: str | None = None,
    org: str | None = None,
) -> CollectResult:
    """Line-resume collector for Claude Code JSONL files."""
    start_line = existing_state.last_line_processed if existing_state else 0
    messages: list[NormalizedMessage] = []
    cwd: str | None = None
    git_branch: str | None = None

    with open(changed.path, "r") as f:
        for line_num, raw_line in enumerate(f, start=1):
            if line_num <= start_line:
                continue
            raw_line = raw_line.strip()
            if not raw_line:
                continue
            try:
                data = json.loads(raw_line)
                if not cwd:
                    cwd = data.get("cwd")
                if not git_branch:
                    git_branch = data.get("gitBranch")
                msgs = transform_claude_v1(data, changed.path, line_num)
                messages.extend(msgs)
            except json.JSONDecodeError as e:
                logger.warning(
                    "Failed to parse line %d of %s: %s", line_num, changed.path, e
                )
                continue
            start_line = line_num

    if messages:
        ctx = _build_session_context(
            cwd=cwd,
            git_branch=git_branch,
            device_name=device_name,
            device_id=device_id,
            global_email=global_email,
            global_name=global_name,
            org=org,
        )
        _attach_context(messages, ctx)

    new_state = FileState(
        file_path=changed.path,
        source=changed.source,
        last_line_processed=start_line,
        last_mtime=changed.mtime,
        last_size=changed.size,
        retry_count=0,
    )
    return CollectResult(messages=messages, new_state=new_state)


def _collect_codex(
    changed: ChangedFile,
    existing_state: FileState | None,
    device_name: str | None = None,
    device_id: str | None = None,
    global_email: str | None = None,
    global_name: str | None = None,
    org: str | None = None,
) -> CollectResult:
    """Line-resume collector for Codex CLI JSONL files with stateful context."""
    start_line = existing_state.last_line_processed if existing_state else 0
    messages: list[NormalizedMessage] = []

    # Reuse cached context if available and consistent with state, otherwise
    # replay from the beginning to rebuild context.
    cached = _codex_context_cache.get(changed.path)
    if cached and cached[0] == start_line:
        replay_from = start_line
        ctx = cached[1]
    else:
        replay_from = 0
        ctx = CodexTransformContext()

    last_line = start_line

    with open(changed.path, "r") as f:
        for line_num, raw_line in enumerate(f, start=1):
            if line_num <= replay_from:
                continue
            raw_line = raw_line.strip()
            if not raw_line:
                continue
            try:
                data = json.loads(raw_line)
                msgs = transform_codex_v1(data, changed.path, line_num, ctx)
                if line_num > start_line:
                    messages.extend(msgs)
            except json.JSONDecodeError as e:
                logger.warning(
                    "Failed to parse line %d of %s: %s", line_num, changed.path, e
                )
                continue
            last_line = line_num

    _codex_context_cache[changed.path] = (last_line, ctx)

    if messages:
        session_ctx = _build_session_context(
            cwd=ctx.cwd,
            git_branch=ctx.git_branch,
            git_commit=ctx.git_commit,
            repo_url=ctx.repo_url,
            device_name=device_name,
            device_id=device_id,
            global_email=global_email,
            global_name=global_name,
            org=org,
        )
        _attach_context(messages, session_ctx)

    new_state = FileState(
        file_path=changed.path,
        source=changed.source,
        last_line_processed=last_line,
        last_mtime=changed.mtime,
        last_size=changed.size,
        retry_count=0,
    )
    return CollectResult(messages=messages, new_state=new_state)


def _collect_gemini(
    changed: ChangedFile,
    existing_state: FileState | None,
    device_name: str | None = None,
    device_id: str | None = None,
    global_email: str | None = None,
    global_name: str | None = None,
    org: str | None = None,
) -> CollectResult:
    """Hash-based collector for Gemini CLI single-JSON session files."""
    content_hash = _hash_file(changed.path)

    # Skip if content hasn't changed
    if existing_state and existing_state.content_hash == content_hash:
        return CollectResult(
            messages=[],
            new_state=FileState(
                file_path=changed.path,
                source=changed.source,
                content_hash=content_hash,
                last_mtime=changed.mtime,
                last_size=changed.size,
                retry_count=0,
            ),
        )

    # Only read file content when we actually need to parse it
    content = _read_file(changed.path)
    messages: list[NormalizedMessage] = []
    project_hash: str | None = None
    try:
        session: dict[str, Any] = json.loads(content)
        project_hash = session.get("projectHash")
        messages = transform_gemini_v1(session, changed.path)
    except json.JSONDecodeError as e:
        logger.warning("Failed to parse %s: %s", changed.path, e)

    if not project_hash:
        project_hash = extract_gemini_hash_from_path(changed.path)

    if messages:
        ctx = _build_session_context(
            device_name=device_name,
            device_id=device_id,
            global_email=global_email,
            global_name=global_name,
            org=org,
        )
        ctx.project_hash = project_hash
        _attach_context(messages, ctx)

    new_state = FileState(
        file_path=changed.path,
        source=changed.source,
        content_hash=content_hash,
        last_mtime=changed.mtime,
        last_size=changed.size,
        retry_count=0,
    )
    return CollectResult(messages=messages, new_state=new_state)


def _collect_cursor(
    changed: ChangedFile,
    existing_state: FileState | None,
    device_name: str | None = None,
    device_id: str | None = None,
    global_email: str | None = None,
    global_name: str | None = None,
    org: str | None = None,
) -> CollectResult:
    """Hash-based collector for Cursor agent transcript text files."""
    content_hash = _hash_file(changed.path)

    # Skip if content hasn't changed
    if existing_state and existing_state.content_hash == content_hash:
        return CollectResult(
            messages=[],
            new_state=FileState(
                file_path=changed.path,
                source=changed.source,
                content_hash=content_hash,
                last_mtime=changed.mtime,
                last_size=changed.size,
                retry_count=0,
            ),
        )

    messages: list[NormalizedMessage] = []
    try:
        transcript = parse_agent_transcript(changed.path)
        messages = transform_cursor_v1(transcript, changed.path)
    except Exception as e:
        logger.warning("Failed to parse %s: %s", changed.path, e)

    if messages:
        cwd: str | None = None
        slug = extract_cursor_slug_from_path(changed.path)
        if slug:
            cwd = decode_cursor_slug(slug)

        ctx = _build_session_context(
            cwd=cwd,
            device_name=device_name,
            device_id=device_id,
            global_email=global_email,
            global_name=global_name,
            org=org,
        )
        _attach_context(messages, ctx)

    new_state = FileState(
        file_path=changed.path,
        source=changed.source,
        content_hash=content_hash,
        last_mtime=changed.mtime,
        last_size=changed.size,
        retry_count=0,
    )
    return CollectResult(messages=messages, new_state=new_state)


def _build_session_context(
    *,
    cwd: str | None = None,
    git_branch: str | None = None,
    git_commit: str | None = None,
    repo_url: str | None = None,
    device_name: str | None = None,
    device_id: str | None = None,
    global_email: str | None = None,
    global_name: str | None = None,
    org: str | None = None,
) -> SessionContext:
    """Build a SessionContext by resolving repo info from cwd.

    Identity chain: local git config > global git config > device_name.
    Pre-provided git fields (from source data) take priority over resolved ones.
    """
    repo_info = None
    if cwd:
        try:
            repo_info = resolve_repo(cwd)
        except Exception as e:
            logger.debug("Failed to resolve repo for %s: %s", cwd, e)

    return SessionContext(
        user_email=(repo_info.user_email if repo_info else None) or global_email,
        user_name=(repo_info.user_name if repo_info else None) or global_name,
        device_name=device_name,
        device_id=device_id,
        cwd=cwd,
        repo_url=repo_url or (repo_info.repo_url if repo_info else None),
        repo_name=(repo_info.repo_name if repo_info else None),
        git_branch=git_branch or (repo_info.git_branch if repo_info else None),
        git_commit=git_commit or (repo_info.git_commit if repo_info else None),
        org=org,
    )


def extract_session_meta(file_path: str, source: str) -> tuple[str | None, str | None]:
    """Lightweight extraction of (session_id, cwd) from a file without full parsing.

    Used by backfill to resolve git metadata for previously-processed sessions.
    """
    if source == "claude_code":
        return _extract_meta_claude(file_path)
    elif source == "codex_cli":
        return _extract_meta_codex(file_path)
    elif source == "cursor":
        return _extract_meta_cursor(file_path)
    return None, None


def _extract_meta_claude(file_path: str) -> tuple[str | None, str | None]:
    """Extract session_id and cwd from first ~10 lines of a Claude Code JSONL file."""
    session_id: str | None = None
    cwd: str | None = None
    try:
        with open(file_path, "r") as f:
            for i, line in enumerate(f):
                if i >= 10:
                    break
                line = line.strip()
                if not line:
                    continue
                try:
                    data = json.loads(line)
                    if not session_id:
                        session_id = data.get("sessionId")
                    if not cwd:
                        cwd = data.get("cwd")
                    if session_id and cwd:
                        break
                except json.JSONDecodeError:
                    continue
    except OSError:
        pass
    return session_id, cwd


def _extract_meta_codex(file_path: str) -> tuple[str | None, str | None]:
    """Extract session_id and cwd from first ~10 lines of a Codex CLI JSONL file."""
    session_id: str | None = None
    cwd: str | None = None
    try:
        with open(file_path, "r") as f:
            for i, line in enumerate(f):
                if i >= 10:
                    break
                line = line.strip()
                if not line:
                    continue
                try:
                    data = json.loads(line)
                    if not session_id:
                        session_id = data.get("id") or data.get("session_id")
                    if not cwd:
                        cwd = data.get("cwd")
                    if session_id and cwd:
                        break
                except json.JSONDecodeError:
                    continue
    except OSError:
        pass
    return session_id, cwd


def _extract_meta_cursor(file_path: str) -> tuple[str | None, str | None]:
    """Extract session_id and cwd from a Cursor transcript file path."""
    import re as _re

    session_id: str | None = None
    cwd: str | None = None

    match = _re.search(r"([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})", file_path)
    if match:
        session_id = match.group(1)

    slug = extract_cursor_slug_from_path(file_path)
    if slug:
        cwd = decode_cursor_slug(slug)

    return session_id, cwd


def _hash_file(path: str, chunk_size: int = 65536) -> str:
    """Compute SHA-256 hash of a file by streaming chunks."""
    h = hashlib.sha256()
    with open(path, "rb") as f:
        while True:
            chunk = f.read(chunk_size)
            if not chunk:
                break
            h.update(chunk)
    return h.hexdigest()


def _read_file(path: str) -> str:
    """Read file contents as string."""
    with open(path, "r") as f:
        return f.read()
