from pathlib import Path

import pytest

from rdb_discovery.tasks import (
    _extract_test_commands_from_claude,
    generate_agent_prompt,
    get_next_task,
)


def _write_claude_with_test_cmds(tmp_path: Path) -> None:
    """Write a CLAUDE.md with Test Commands section."""
    (tmp_path / "CLAUDE.md").write_text(
        "# Claude Code Instructions\n\n"
        "## Test Commands\n\n"
        "Use the existing virtual environment.\n\n"
        "```bash\n"
        "source .venv/bin/activate\n"
        "python -m pytest\n"
        "```\n",
        encoding="utf-8",
    )


def test_generate_agent_prompt_includes_task_info(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: First goal.\n\n"
        "Acceptance Criteria:\n"
        "- a\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: Second goal.\n\n"
        "Acceptance Criteria:\n"
        "- b\n"
        "- c\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "TASK-002" in prompt
    assert "Second" in prompt
    assert "Todo" in prompt
    assert "Second goal." in prompt


def test_generate_agent_prompt_includes_acceptance_criteria(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: x.\n\n"
        "Acceptance Criteria:\n"
        "- alpha\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n\n"
        "Acceptance Criteria:\n"
        "- bravo\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "- alpha" not in prompt
    assert "- bravo" in prompt


def test_generate_agent_prompt_includes_read_instructions(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: x.\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "README.md" in prompt
    assert "TASKS.md" in prompt
    assert "PROJECT_STATE.md" in prompt
    assert "AGENT_HANDOFF.md" in prompt
    assert "context/agent-guidelines.md" in prompt


def test_generate_agent_prompt_includes_one_step_constraint(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: x.\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "ONE small implementation step only" in prompt


def test_generate_agent_prompt_includes_validation(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: x.\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "Validation" in prompt
    assert "pytest" in prompt


def test_generate_agent_prompt_includes_reporting(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: x.\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "Reporting" in prompt


def test_generate_agent_prompt_no_todo_task(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert prompt == "No Todo task found."


def test_generate_agent_prompt_no_tasks_file(tmp_path: Path) -> None:
    prompt = generate_agent_prompt(tmp_path)

    assert prompt == "No Todo task found."


def test_generate_agent_prompt_includes_implementation_gap(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: x.\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n"
        "Implementation Gap:\n"
        "Missing validation handler in cli.py\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "Implementation Gap:" in prompt
    assert "Missing validation handler in cli.py" in prompt


def test_generate_agent_prompt_omits_gap_when_missing(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "Goal: x.\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "Implementation Gap:" not in prompt


def test_generate_agent_prompt_includes_test_commands_from_claude(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )
    _write_claude_with_test_cmds(tmp_path)

    prompt = generate_agent_prompt(tmp_path)

    assert "Test Commands (from CLAUDE.md)" in prompt
    assert "source .venv/bin/activate" in prompt
    assert "python -m pytest" in prompt


def test_generate_agent_prompt_includes_no_reread_constraint(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "reread" in prompt.lower() or "read" in prompt.lower()


def test_generate_agent_prompt_includes_inspect_first_constraint(tmp_path: Path) -> None:
    (tmp_path / "TASKS.md").write_text(
        "# TASKS\n\n"
        "## TASK-001 — First\nStatus: Done\n\n"
        "## TASK-002 — Second\nStatus: Todo\n\n"
        "Goal: y.\n",
        encoding="utf-8",
    )

    prompt = generate_agent_prompt(tmp_path)

    assert "Inspect" in prompt or "inspect" in prompt


def test_extract_test_commands_no_claude_file(tmp_path: Path) -> None:
    commands = _extract_test_commands_from_claude(tmp_path)
    assert commands == []


def test_extract_test_commands_from_claude(tmp_path: Path) -> None:
    (tmp_path / "CLAUDE.md").write_text(
        "# Instructions\n\n"
        "## Test Commands\n\n"
        "Run the following:\n\n"
        "```bash\n"
        "source .venv/bin/activate\n"
        "python -m pytest\n"
        "```\n",
        encoding="utf-8",
    )

    commands = _extract_test_commands_from_claude(tmp_path)

    assert any(".venv/bin/activate" in cmd for cmd in commands)
    assert "python -m pytest" in commands


def test_extract_test_commands_no_section(tmp_path: Path) -> None:
    (tmp_path / "CLAUDE.md").write_text(
        "# Instructions\n\n"
        "No test section here.\n",
        encoding="utf-8",
    )

    commands = _extract_test_commands_from_claude(tmp_path)
    assert commands == []