"""
Session export generators for ResolutionFlow.

Provides markdown, plain text, HTML, and PSA/ticket note export formatters
for troubleshooting sessions.
"""
import html
from datetime import datetime
from typing import Any

from app.models.session import Session
from app.schemas.session import SessionExport


OUTCOME_LABELS = {
    "resolved": "Resolved",
    "escalated": "Escalated",
    "workaround": "Workaround Applied",
    "unresolved": "Unresolved",
}


def _format_duration(started_at: datetime, completed_at: datetime | None) -> str:
    """Format duration between two datetimes as human-readable string."""
    if not completed_at:
        return "In progress"
    delta = completed_at - started_at
    total_seconds = int(delta.total_seconds())
    if total_seconds < 0:
        return "0 minutes"
    hours, remainder = divmod(total_seconds, 3600)
    minutes = remainder // 60
    if hours > 0:
        return f"{hours}h {minutes}m"
    return f"{minutes} minutes"


def _format_step_duration(duration_seconds: int) -> str:
    """Format step duration seconds as compact human-readable text."""
    if duration_seconds < 0:
        return "0s"
    if duration_seconds < 60:
        return f"{duration_seconds}s"
    hours, remainder = divmod(duration_seconds, 3600)
    minutes, seconds = divmod(remainder, 60)
    if hours > 0:
        if seconds > 0:
            return f"{hours}h {minutes}m {seconds}s"
        return f"{hours}h {minutes}m"
    if seconds > 0:
        return f"{minutes}m {seconds}s"
    return f"{minutes}m"


def _parse_iso_datetime(value: Any) -> datetime | None:
    """Parse ISO datetime strings from JSONB with support for trailing Z."""
    if isinstance(value, datetime):
        return value
    if not isinstance(value, str) or not value:
        return None
    try:
        return datetime.fromisoformat(value.replace("Z", "+00:00"))
    except ValueError:
        return None


def _get_step_duration_seconds(decision: dict[str, Any]) -> int | None:
    """Get step duration from explicit field or entered/exited timestamps."""
    explicit_duration = decision.get("duration_seconds")
    if isinstance(explicit_duration, (int, float)):
        duration = int(explicit_duration)
        if duration >= 0:
            return duration

    entered_at = _parse_iso_datetime(decision.get("entered_at"))
    exited_at = _parse_iso_datetime(decision.get("exited_at"))
    if entered_at and exited_at:
        total_seconds = int((exited_at - entered_at).total_seconds())
        if total_seconds >= 0:
            return total_seconds
    return None


def _get_command_output(decision: dict[str, Any]) -> str | None:
    """Extract and normalize command_output from a decision dict."""
    output = decision.get("command_output")
    if not isinstance(output, str):
        return None
    output = output.strip()
    return output if output else None


def _find_node_commands(tree_snapshot: dict[str, Any], node_id: str) -> list[str]:
    """Find the commands list for a node in the tree snapshot."""
    def _search(node: dict[str, Any]) -> list[str] | None:
        if node.get("id") == node_id:
            return node.get("commands") or []
        for child in node.get("children", []):
            result = _search(child)
            if result is not None:
                return result
        return None

    structure = tree_snapshot.get("tree_structure") or tree_snapshot
    return _search(structure) or []


def _get_outcome_label(session: Session) -> str | None:
    """Map stored outcome enum to human-friendly label."""
    outcome = getattr(session, "outcome", None)
    if not outcome:
        return None
    return OUTCOME_LABELS.get(outcome, str(outcome).replace("_", " ").title())


def generate_markdown_export(session: Session, options: SessionExport) -> str:
    """Generate markdown export."""
    lines = []
    outcome_label = _get_outcome_label(session)

    if options.include_tree_info:
        tree_name = session.tree_snapshot.get("name", "Troubleshooting Session")
        lines.append(f"# {tree_name}")
        lines.append("")
        if session.ticket_number:
            lines.append(f"**Ticket:** {session.ticket_number}")
        if session.client_name:
            lines.append(f"**Client:** {session.client_name}")
        if options.include_timestamps:
            lines.append(f"**Started:** {session.started_at.strftime('%Y-%m-%d %H:%M')}")
            if session.completed_at:
                lines.append(f"**Completed:** {session.completed_at.strftime('%Y-%m-%d %H:%M')}")
        lines.append(f"**Duration:** {_format_duration(session.started_at, session.completed_at)}")
        if outcome_label:
            lines.append(f"**Outcome:** {outcome_label}")
        lines.append("")
        lines.append("---")
        lines.append("")

    # Scratchpad / Evidence section
    scratchpad = getattr(session, 'scratchpad', '') or ''
    if scratchpad.strip():
        lines.append("## Evidence / Reference")
        lines.append("")
        lines.append(scratchpad)
        lines.append("")
        lines.append("---")
        lines.append("")

    lines.append("## Troubleshooting Steps")
    lines.append("")

    decisions = session.decisions
    if options.max_step_index is not None:
        decisions = decisions[:options.max_step_index]

    for i, decision in enumerate(decisions, 1):
        question = decision.get("question") or decision.get("action_performed", "Step")
        answer = decision.get("answer", "")
        notes = decision.get("notes", "")
        duration_seconds = _get_step_duration_seconds(decision)

        lines.append(f"### Step {i}: {question}")
        if answer:
            lines.append(f"**Answer:** {answer}")
        if notes:
            lines.append(f"**Notes:** {notes}")
        if command_output := _get_command_output(decision):
            commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
            if commands:
                lines.append(f"**Commands Run:** {', '.join(f'`{c}`' for c in commands)}")
            lines.append("**Output:**")
            lines.append("```")
            lines.append(command_output)
            lines.append("```")
        if duration_seconds is not None:
            lines.append(f"**Duration:** {_format_step_duration(duration_seconds)}")
        if options.include_timestamps and decision.get("timestamp"):
            lines.append(f"*{decision['timestamp']}*")
        lines.append("")

    # Resolution / Outcome Notes
    _raw_notes = getattr(session, 'outcome_notes', None)
    outcome_notes = _raw_notes if isinstance(_raw_notes, str) else ''
    if outcome_notes.strip() and options.include_outcome_notes:
        lines.append("---")
        lines.append("")
        lines.append("## Resolution")
        lines.append("")
        lines.append(outcome_notes.strip())
        lines.append("")

    # Next Steps
    _raw_next = getattr(session, 'next_steps', None)
    next_steps = _raw_next if isinstance(_raw_next, str) else ''
    if next_steps.strip() and options.include_next_steps:
        lines.append("---")
        lines.append("")
        lines.append("## Next Steps")
        lines.append("")
        lines.append(next_steps.strip())
        lines.append("")

    return "\n".join(lines)


def generate_text_export(session: Session, options: SessionExport) -> str:
    """Generate plain text export."""
    lines = []
    outcome_label = _get_outcome_label(session)

    if options.include_tree_info:
        tree_name = session.tree_snapshot.get("name", "Troubleshooting Session")
        lines.append(tree_name)
        lines.append("=" * len(tree_name))
        if session.ticket_number:
            lines.append(f"Ticket: {session.ticket_number}")
        if session.client_name:
            lines.append(f"Client: {session.client_name}")
        if options.include_timestamps:
            lines.append(f"Started: {session.started_at.strftime('%Y-%m-%d %H:%M')}")
            if session.completed_at:
                lines.append(f"Completed: {session.completed_at.strftime('%Y-%m-%d %H:%M')}")
        lines.append(f"Duration: {_format_duration(session.started_at, session.completed_at)}")
        if outcome_label:
            lines.append(f"Outcome: {outcome_label}")
        lines.append("")

    # Scratchpad / Evidence section
    scratchpad = getattr(session, 'scratchpad', '') or ''
    if scratchpad.strip():
        lines.append("EVIDENCE / REFERENCE")
        lines.append("-" * 20)
        lines.append(scratchpad)
        lines.append("")

    lines.append("TROUBLESHOOTING STEPS")
    lines.append("-" * 20)

    decisions = session.decisions
    if options.max_step_index is not None:
        decisions = decisions[:options.max_step_index]

    for i, decision in enumerate(decisions, 1):
        question = decision.get("question") or decision.get("action_performed", "Step")
        answer = decision.get("answer", "")
        notes = decision.get("notes", "")
        duration_seconds = _get_step_duration_seconds(decision)

        lines.append(f"\n{i}. {question}")
        if answer:
            lines.append(f"   Answer: {answer}")
        if notes:
            lines.append(f"   Notes: {notes}")
        if command_output := _get_command_output(decision):
            commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
            if commands:
                lines.append(f"   Commands Run: {', '.join(commands)}")
            lines.append("   Output:")
            for output_line in command_output.splitlines():
                lines.append(f"     {output_line}")
        if duration_seconds is not None:
            lines.append(f"   Duration: {_format_step_duration(duration_seconds)}")

    # Resolution
    _raw_notes = getattr(session, 'outcome_notes', None)
    outcome_notes = _raw_notes if isinstance(_raw_notes, str) else ''
    if outcome_notes.strip() and options.include_outcome_notes:
        lines.append("")
        lines.append("RESOLUTION")
        lines.append("-" * 20)
        lines.append(outcome_notes.strip())

    # Next Steps
    _raw_next = getattr(session, 'next_steps', None)
    next_steps = _raw_next if isinstance(_raw_next, str) else ''
    if next_steps.strip() and options.include_next_steps:
        lines.append("")
        lines.append("NEXT STEPS")
        lines.append("-" * 20)
        lines.append(next_steps.strip())

    return "\n".join(lines)


def generate_html_export(session: Session, options: SessionExport) -> str:
    """Generate HTML export."""
    tree_name = html.escape(session.tree_snapshot.get("name", "Troubleshooting Session"))
    outcome_label = _get_outcome_label(session)

    html_parts = ['<!DOCTYPE html>', '<html>', '<head>',
            '<meta charset="UTF-8">',
            f'<title>{tree_name}</title>',
            '<style>',
            'body { font-family: Arial, sans-serif; max-width: 800px; margin: 0 auto; padding: 20px; }',
            'h1 { color: #333; }',
            '.meta { color: #666; margin-bottom: 20px; }',
            '.step { margin-bottom: 15px; padding: 10px; background: #f5f5f5; border-radius: 5px; }',
            '.step h3 { margin: 0 0 10px 0; color: #444; }',
            '.answer { font-weight: bold; }',
            '.notes { font-style: italic; color: #555; }',
            '.duration { color: #444; margin-top: 6px; }',
            '.timestamp { font-size: 0.85em; color: #888; }',
            '</style>',
            '</head>', '<body>']

    if options.include_tree_info:
        html_parts.append(f'<h1>{tree_name}</h1>')
        html_parts.append('<div class="meta">')
        if session.ticket_number:
            html_parts.append(f'<p><strong>Ticket:</strong> {html.escape(session.ticket_number)}</p>')
        if session.client_name:
            html_parts.append(f'<p><strong>Client:</strong> {html.escape(session.client_name)}</p>')
        if options.include_timestamps:
            html_parts.append(f'<p><strong>Started:</strong> {session.started_at.strftime("%Y-%m-%d %H:%M")}</p>')
            if session.completed_at:
                html_parts.append(f'<p><strong>Completed:</strong> {session.completed_at.strftime("%Y-%m-%d %H:%M")}</p>')
        html_parts.append(f'<p><strong>Duration:</strong> {_format_duration(session.started_at, session.completed_at)}</p>')
        if outcome_label:
            html_parts.append(f'<p><strong>Outcome:</strong> {html.escape(outcome_label)}</p>')
        html_parts.append('</div>')

    # Scratchpad / Evidence section
    scratchpad = getattr(session, 'scratchpad', '') or ''
    if scratchpad.strip():
        html_parts.append('<h2>Evidence / Reference</h2>')
        html_parts.append(f'<div class="scratchpad" style="white-space: pre-wrap; background: #f9f9f9; padding: 12px; border-radius: 4px; margin-bottom: 20px;">{html.escape(scratchpad)}</div>')

    html_parts.append('<h2>Troubleshooting Steps</h2>')

    decisions = session.decisions
    if options.max_step_index is not None:
        decisions = decisions[:options.max_step_index]

    for i, decision in enumerate(decisions, 1):
        question = html.escape(decision.get("question") or decision.get("action_performed", "Step"))
        answer = html.escape(decision.get("answer", ""))
        notes = html.escape(decision.get("notes", ""))
        duration_seconds = _get_step_duration_seconds(decision)

        html_parts.append('<div class="step">')
        html_parts.append(f'<h3>Step {i}: {question}</h3>')
        if answer:
            html_parts.append(f'<p class="answer">Answer: {answer}</p>')
        if notes:
            html_parts.append(f'<p class="notes">Notes: {notes}</p>')
        if command_output := _get_command_output(decision):
            commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
            if commands:
                cmd_html = ", ".join(f"<code>{html.escape(c)}</code>" for c in commands)
                html_parts.append(f'<p><strong>Commands Run:</strong> {cmd_html}</p>')
            html_parts.append(f'<pre><code>{html.escape(command_output)}</code></pre>')
        if duration_seconds is not None:
            html_parts.append(f'<p class="duration"><strong>Duration:</strong> {_format_step_duration(duration_seconds)}</p>')
        if options.include_timestamps and decision.get("timestamp"):
            html_parts.append(f'<p class="timestamp">{html.escape(str(decision["timestamp"]))}</p>')
        html_parts.append('</div>')

    # Resolution
    _raw_notes = getattr(session, 'outcome_notes', None)
    outcome_notes = _raw_notes if isinstance(_raw_notes, str) else ''
    if outcome_notes.strip() and options.include_outcome_notes:
        html_parts.append('<h2>Resolution</h2>')
        html_parts.append(f'<div style="white-space: pre-wrap; margin-bottom: 20px;">{html.escape(outcome_notes.strip())}</div>')

    # Next Steps
    _raw_next = getattr(session, 'next_steps', None)
    next_steps = _raw_next if isinstance(_raw_next, str) else ''
    if next_steps.strip() and options.include_next_steps:
        html_parts.append('<h2>Next Steps</h2>')
        html_parts.append(f'<div style="white-space: pre-wrap; margin-bottom: 20px;">{html.escape(next_steps.strip())}</div>')

    html_parts.extend(['</body>', '</html>'])
    return "\n".join(html_parts)


def generate_psa_export(session: Session, options: SessionExport) -> str:
    """Generate PSA/ticket note export optimized for ConnectWise and similar PSA tools."""
    lines = []
    outcome_label = _get_outcome_label(session)

    tree_name = session.tree_snapshot.get("name", "Troubleshooting Session")
    tree_description = session.tree_snapshot.get("description", "")
    ticket_number = session.ticket_number or "N/A"
    client_name = session.client_name or "N/A"
    date_str = session.started_at.strftime("%Y-%m-%d %H:%M")

    lines.append("=== TROUBLESHOOTING NOTES ===")
    lines.append(f"Ticket: {ticket_number}  |  Client: {client_name}")
    lines.append(f"Tree: {tree_name}  |  Date: {date_str}")
    lines.append(f"Duration: {_format_duration(session.started_at, session.completed_at)}")
    if outcome_label:
        lines.append(f"Outcome: {outcome_label}")
    lines.append("")

    # Problem section
    lines.append("--- PROBLEM ---")
    lines.append(tree_description if tree_description else "No description provided.")
    lines.append("")

    # Steps taken
    lines.append("--- STEPS TAKEN ---")
    decisions = session.decisions
    if options.max_step_index is not None:
        decisions = decisions[:options.max_step_index]
    if decisions:
        for i, decision in enumerate(decisions, 1):
            question = decision.get("question") or decision.get("action_performed", "Step")
            answer = decision.get("answer", "")
            notes = decision.get("notes", "")
            duration_seconds = _get_step_duration_seconds(decision)

            line = f"{i}. {question}"
            if answer:
                line += f" -> {answer}"
            if duration_seconds is not None:
                line += f" ({_format_step_duration(duration_seconds)})"
            lines.append(line)
            if notes:
                lines.append(f"   Notes: {notes}")
            if command_output := _get_command_output(decision):
                commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
                if commands:
                    lines.append(f"   Commands: {', '.join(commands)}")
                lines.append("   Output:")
                for output_line in command_output.splitlines():
                    lines.append(f"     {output_line}")
    else:
        lines.append("No steps recorded.")
    lines.append("")

    # Resolution
    lines.append("--- RESOLUTION ---")
    _raw_notes = getattr(session, 'outcome_notes', None)
    outcome_notes = _raw_notes if isinstance(_raw_notes, str) else ''
    if outcome_notes.strip() and options.include_outcome_notes:
        lines.append(outcome_notes.strip())
    elif session.decisions:
        last_decision = session.decisions[-1]
        resolution = last_decision.get("answer") or last_decision.get("question", "No resolution recorded")
        lines.append(resolution)
    else:
        lines.append("No resolution recorded.")
    if outcome_label:
        lines.append(f"Outcome: {outcome_label}")
    lines.append("")

    # Next Steps
    _raw_next = getattr(session, 'next_steps', None)
    next_steps = _raw_next if isinstance(_raw_next, str) else ''
    if next_steps.strip() and options.include_next_steps:
        lines.append("--- NEXT STEPS ---")
        lines.append(next_steps.strip())
        lines.append("")

    # Time spent
    lines.append("--- TIME SPENT ---")
    duration = _format_duration(session.started_at, session.completed_at)
    lines.append(f"Duration: {duration}")
    lines.append("")

    # Engineer notes (scratchpad)
    lines.append("--- ENGINEER NOTES ---")
    scratchpad = getattr(session, 'scratchpad', '') or ''
    lines.append(scratchpad.strip() if scratchpad.strip() else "None")

    return "\n".join(lines)