from __future__ import annotations

import fnmatch
import re
from enum import StrEnum
from pathlib import Path
from typing import Any, Iterable

from pydantic import BaseModel, ConfigDict, Field

from app.mailer.campaign.entries import load_campaign_entries
from app.mailer.campaign.field_values import effective_entry_field_values
from app.mailer.campaign.models import AttachmentConfig, Behavior, CampaignConfig, EntryConfig


class AttachmentScope(StrEnum):
    GLOBAL = "global"
    ENTRY = "entry"


class AttachmentMatchStatus(StrEnum):
    OK = "ok"
    MISSING = "missing"
    AMBIGUOUS = "ambiguous"


class MessageAttachmentStatus(StrEnum):
    READY = "ready"
    WARNING = "warning"
    NEEDS_REVIEW = "needs_review"
    BLOCKED = "blocked"
    EXCLUDED = "excluded"
    INACTIVE = "inactive"


class ResolutionSeverity(StrEnum):
    INFO = "info"
    WARNING = "warning"
    ERROR = "error"


class AttachmentIssue(BaseModel):
    model_config = ConfigDict(extra="forbid")

    severity: ResolutionSeverity
    code: str
    message: str
    behavior: Behavior | None = None


class ResolvedAttachment(BaseModel):
    model_config = ConfigDict(extra="forbid")

    scope: AttachmentScope
    index: int
    attachment_id: str | None = None
    label: str | None = None
    base_dir_template: str
    file_filter_template: str
    base_dir: str
    file_filter: str
    directory: str
    include_subdirs: bool
    required: bool
    allow_multiple: bool
    zip_enabled: bool
    status: AttachmentMatchStatus
    behavior: Behavior | None = None
    matches: list[str] = Field(default_factory=list)
    issues: list[AttachmentIssue] = Field(default_factory=list)


class EntryAttachmentResolution(BaseModel):
    model_config = ConfigDict(extra="forbid")

    entry_index: int
    entry_id: str | None = None
    active: bool
    status: MessageAttachmentStatus
    attachments: list[ResolvedAttachment] = Field(default_factory=list)
    issues: list[AttachmentIssue] = Field(default_factory=list)

    @property
    def match_count(self) -> int:
        return sum(len(item.matches) for item in self.attachments)


class AttachmentResolutionReport(BaseModel):
    model_config = ConfigDict(extra="forbid")

    campaign_id: str
    campaign_name: str
    campaign_file: str
    attachments_base_path: str
    entries_count: int
    entries: list[EntryAttachmentResolution] = Field(default_factory=list)

    @property
    def ready_count(self) -> int:
        return sum(1 for entry in self.entries if entry.status == MessageAttachmentStatus.READY)

    @property
    def warning_count(self) -> int:
        return sum(1 for entry in self.entries if entry.status == MessageAttachmentStatus.WARNING)

    @property
    def needs_review_count(self) -> int:
        return sum(1 for entry in self.entries if entry.status == MessageAttachmentStatus.NEEDS_REVIEW)

    @property
    def blocked_count(self) -> int:
        return sum(1 for entry in self.entries if entry.status == MessageAttachmentStatus.BLOCKED)

    @property
    def excluded_count(self) -> int:
        return sum(1 for entry in self.entries if entry.status == MessageAttachmentStatus.EXCLUDED)

    @property
    def inactive_count(self) -> int:
        return sum(1 for entry in self.entries if entry.status == MessageAttachmentStatus.INACTIVE)


def _resolve_path(campaign_file: str | Path, raw_path: str) -> Path:
    campaign_path = Path(campaign_file).resolve()
    path = Path(raw_path).expanduser()
    if path.is_absolute():
        return path
    return (campaign_path.parent / path).resolve()


_DOLLAR_FIELD_PATTERN = re.compile(r"(?<!\\)\$\{(.*?)(?<!\\)\}")
_BRACE_FIELD_PATTERN = re.compile(r"(?<!\\)\{\{\s*(.*?)\s*\}\}")


def _normalize_template_key(raw: str) -> str:
    key = raw.strip()
    if key.startswith("fields."):
        key = key.removeprefix("fields.")
    elif key.startswith("local."):
        key = "local::" + key.removeprefix("local.")
    elif key.startswith("global."):
        key = "global::" + key.removeprefix("global.")

    if key.startswith("local::") or key.startswith("global::"):
        return key
    if key.startswith("local:"):
        return "local::" + key.removeprefix("local:")
    if key.startswith("global:"):
        return "global::" + key.removeprefix("global:")
    return key


def _render_template(template: str, values: dict[str, Any]) -> str:
    def replace(match: re.Match[str]) -> str:
        key = _normalize_template_key(match.group(1))
        if key in values:
            value = values[key]
            return "" if value is None else str(value)
        return match.group(0)

    rendered = _DOLLAR_FIELD_PATTERN.sub(replace, template)
    rendered = _BRACE_FIELD_PATTERN.sub(replace, rendered)
    return rendered.replace(r"\${", "${").replace(r"\}", "}")


def _recipient_values(entry: EntryConfig) -> dict[str, str]:
    values: dict[str, str] = {}
    for list_name in ["to", "cc", "bcc", "reply_to", "bounce_to", "disposition_notification_to"]:
        recipients = getattr(entry, list_name)
        for index, recipient in enumerate(recipients):
            prefix = f"{list_name}.{index}"
            values[f"local::{prefix}.email"] = recipient.email
            values[f"local::{prefix}.name"] = recipient.name or ""
            values[f"local::{prefix}.type"] = recipient.recipient_type.value
    if entry.from_:
        values["local::from.email"] = entry.from_.email
        values["local::from.name"] = entry.from_.name or ""
        values["local::from.type"] = entry.from_.recipient_type.value
    return values


def _template_values(config: CampaignConfig, entry: EntryConfig) -> dict[str, Any]:
    values: dict[str, Any] = {}
    for key, value in config.global_values.items():
        values[f"global::{key}"] = value
    for key, value in effective_entry_field_values(config, entry).items():
        values[f"local::{key}"] = value
    if entry.id:
        values["local::id"] = entry.id
    values["local::active"] = entry.active
    values.update(_recipient_values(entry))
    return values


def _iter_effective_attachment_configs(config: CampaignConfig, entry: EntryConfig) -> Iterable[tuple[AttachmentScope, int, AttachmentConfig]]:
    if entry.combine_attachments:
        for index, attachment_config in enumerate(config.attachments.global_):
            yield AttachmentScope.GLOBAL, index, attachment_config
    if config.attachments.allow_individual:
        for index, attachment_config in enumerate(entry.attachments):
            yield AttachmentScope.ENTRY, index, attachment_config


def _match_files(directory: Path, file_filter: str, include_subdirs: bool) -> list[Path]:
    if not directory.exists() or not directory.is_dir():
        return []
    if include_subdirs:
        # pathlib.rglob accepts glob patterns, but fnmatch keeps behavior predictable
        # when file_filter is supplied as the Java-style filter portion only.
        return sorted(path for path in directory.rglob("*") if path.is_file() and fnmatch.fnmatch(path.name, file_filter))
    return sorted(path for path in directory.glob(file_filter) if path.is_file())


def _issue_for_missing(config: AttachmentConfig, behavior: Behavior) -> AttachmentIssue:
    code = "missing_required_attachment" if config.required else "missing_optional_attachment"
    severity = ResolutionSeverity.ERROR if config.required and behavior == Behavior.BLOCK else ResolutionSeverity.WARNING
    return AttachmentIssue(
        severity=severity,
        code=code,
        message=f"No file matched attachment filter {config.file_filter!r}",
        behavior=behavior,
    )


def _issue_for_ambiguous(config: AttachmentConfig, behavior: Behavior, match_count: int) -> AttachmentIssue:
    severity = ResolutionSeverity.ERROR if behavior == Behavior.BLOCK else ResolutionSeverity.WARNING
    return AttachmentIssue(
        severity=severity,
        code="ambiguous_attachment_match",
        message=f"Attachment filter {config.file_filter!r} matched {match_count} files, but allow_multiple is false",
        behavior=behavior,
    )


def _resolve_one_config(
    *,
    campaign_file: str | Path,
    attachments_base_path: Path,
    values: dict[str, Any],
    scope: AttachmentScope,
    index: int,
    config: AttachmentConfig,
) -> ResolvedAttachment:
    rendered_base_dir = _render_template(config.base_dir, values)
    rendered_file_filter = _render_template(config.file_filter, values)
    directory = (attachments_base_path / rendered_base_dir).resolve()
    matches = _match_files(directory, rendered_file_filter, config.include_subdirs)

    issues: list[AttachmentIssue] = []
    behavior: Behavior | None = None

    if not matches:
        status = AttachmentMatchStatus.MISSING
        behavior = config.missing_behavior
        issues.append(_issue_for_missing(config, behavior))
    elif len(matches) > 1 and not config.allow_multiple:
        status = AttachmentMatchStatus.AMBIGUOUS
        behavior = config.ambiguous_behavior
        issues.append(_issue_for_ambiguous(config, behavior, len(matches)))
    else:
        status = AttachmentMatchStatus.OK

    return ResolvedAttachment(
        scope=scope,
        index=index,
        attachment_id=config.id,
        label=config.label,
        base_dir_template=config.base_dir,
        file_filter_template=config.file_filter,
        base_dir=rendered_base_dir,
        file_filter=rendered_file_filter,
        directory=str(directory),
        include_subdirs=config.include_subdirs,
        required=config.required,
        allow_multiple=config.allow_multiple,
        zip_enabled=config.zip.enabled,
        status=status,
        behavior=behavior,
        matches=[str(path) for path in matches],
        issues=issues,
    )


def _status_from_issues(active: bool, issues: list[AttachmentIssue]) -> MessageAttachmentStatus:
    if not active:
        return MessageAttachmentStatus.INACTIVE
    behaviors = {issue.behavior for issue in issues if issue.behavior is not None}
    if Behavior.BLOCK in behaviors:
        return MessageAttachmentStatus.BLOCKED
    if Behavior.DROP in behaviors:
        return MessageAttachmentStatus.EXCLUDED
    if Behavior.ASK in behaviors:
        return MessageAttachmentStatus.NEEDS_REVIEW
    if Behavior.WARN in behaviors:
        return MessageAttachmentStatus.WARNING
    return MessageAttachmentStatus.READY


def resolve_entry_attachments(
    *,
    config: CampaignConfig,
    campaign_file: str | Path,
    entry: EntryConfig,
    entry_index: int,
) -> EntryAttachmentResolution:
    attachments_base_path = _resolve_path(campaign_file, config.attachments.base_path)
    values = _template_values(config, entry)
    resolved: list[ResolvedAttachment] = []

    if entry.active:
        for scope, index, attachment_config in _iter_effective_attachment_configs(config, entry):
            resolved.append(
                _resolve_one_config(
                    campaign_file=campaign_file,
                    attachments_base_path=attachments_base_path,
                    values=values,
                    scope=scope,
                    index=index,
                    config=attachment_config,
                )
            )

    issues = [issue for item in resolved for issue in item.issues]
    return EntryAttachmentResolution(
        entry_index=entry_index,
        entry_id=entry.id,
        active=entry.active,
        status=_status_from_issues(entry.active, issues),
        attachments=resolved,
        issues=issues,
    )


def resolve_campaign_attachments(config: CampaignConfig, *, campaign_file: str | Path) -> AttachmentResolutionReport:
    entries = load_campaign_entries(config, campaign_file=campaign_file)
    base_path = _resolve_path(campaign_file, config.attachments.base_path)
    resolved_entries = [
        resolve_entry_attachments(config=config, campaign_file=campaign_file, entry=entry, entry_index=index)
        for index, entry in enumerate(entries, start=1)
    ]
    return AttachmentResolutionReport(
        campaign_id=config.campaign.id,
        campaign_name=config.campaign.name,
        campaign_file=str(Path(campaign_file).resolve()),
        attachments_base_path=str(base_path),
        entries_count=len(entries),
        entries=resolved_entries,
    )