import os
from typing import Callable
from typing import Optional

from ddtrace.constants import ENV_KEY
from ddtrace.constants import VERSION_KEY
from ddtrace.internal.logger import get_logger


log = get_logger(__name__)


OTEL_UNIFIED_TAG_MAPPINGS = {
    "deployment.environment": ENV_KEY,
    "service.name": "service",
    "service.version": VERSION_KEY,
}


def _remap_otel_log_level(otel_value: str) -> Optional[str]:
    """Remaps the otel log level to ddtrace log level"""
    if otel_value == "debug":
        return "True"
    return None


def _remap_otel_propagators(otel_value: str) -> Optional[str]:
    """Remaps the otel propagators to ddtrace propagators"""
    accepted_styles = []
    for style in otel_value.split(","):
        style = style.strip().lower()
        if style in ["b3", "b3multi", "datadog", "tracecontext", "none"]:
            if style not in accepted_styles:
                accepted_styles.append(style)
        else:
            log.warning("Following style not supported by ddtrace: %s.", style)
    return ",".join(accepted_styles) or None


def _remap_traces_sampler(otel_value: str) -> Optional[str]:
    """Remaps the otel trace sampler to ddtrace trace sampler"""
    if otel_value in ["always_on", "always_off", "traceidratio"]:
        log.warning(
            "Trace sampler set from %s to parentbased_%s; only parent based sampling is supported.",
            otel_value,
            otel_value,
        )
        otel_value = f"parentbased_{otel_value}"
    rate = None
    if otel_value == "parentbased_always_on":
        rate = "1.0"
    elif otel_value == "parentbased_always_off":
        rate = "0.0"
    elif otel_value == "parentbased_traceidratio":
        rate = os.environ.get("OTEL_TRACES_SAMPLER_ARG", "1")

    if rate is not None:
        return f'[{{"sample_rate":{rate}}}]'
    return None


def _remap_traces_exporter(otel_value: str) -> Optional[str]:
    """Remaps the otel trace exporter to ddtrace trace enabled"""
    if otel_value == "none":
        return "False"
    return None


def _remap_metrics_exporter(otel_value: str) -> Optional[str]:
    """Remaps the otel metrics exporter to ddtrace metrics exporter"""
    if otel_value == "none":
        return "False"
    return None


def _remap_otel_tags(otel_value: str) -> Optional[str]:
    """Remaps the otel tags to ddtrace tags"""
    dd_tags: list[str] = []

    try:
        otel_user_tag_dict: dict[str, str] = dict()
        for tag in otel_value.split(","):
            key, value = tag.split("=")
            otel_user_tag_dict[key] = value

        for key, value in otel_user_tag_dict.items():
            if key.lower() in OTEL_UNIFIED_TAG_MAPPINGS:
                dd_key = OTEL_UNIFIED_TAG_MAPPINGS[key.lower()]
                dd_tags.insert(0, f"{dd_key}:{value}")
            else:
                dd_tags.append(f"{key}:{value}")
    except Exception:
        return None

    if len(dd_tags) > 10:
        dd_tags, remaining_tags = dd_tags[:10], dd_tags[10:]
        log.warning(
            "To preserve metrics cardinality, only the following first 10 tags have been processed %s. "
            "The following tags were not ingested: %s",
            dd_tags,
            remaining_tags,
        )
    return ",".join(dd_tags)


def _remap_otel_sdk_config(otel_value: str) -> Optional[str]:
    """Remaps the otel sdk config to ddtrace sdk config"""
    if otel_value == "false":
        return "True"
    elif otel_value == "true":
        return "False"
    return None


def _remap_default(otel_value: str) -> Optional[str]:
    """Remaps the otel default value to ddtrace default value"""
    return otel_value


ENV_VAR_MAPPINGS: dict[str, tuple[str, Callable[[str], Optional[str]]]] = {
    "OTEL_SERVICE_NAME": ("DD_SERVICE", _remap_default),
    "OTEL_LOG_LEVEL": ("DD_TRACE_DEBUG", _remap_otel_log_level),
    "OTEL_PROPAGATORS": ("DD_TRACE_PROPAGATION_STYLE", _remap_otel_propagators),
    "OTEL_TRACES_SAMPLER": ("DD_TRACE_SAMPLING_RULES", _remap_traces_sampler),
    "OTEL_TRACES_EXPORTER": ("DD_TRACE_ENABLED", _remap_traces_exporter),
    "OTEL_METRICS_EXPORTER": ("DD_RUNTIME_METRICS_ENABLED", _remap_metrics_exporter),
    "OTEL_RESOURCE_ATTRIBUTES": ("DD_TAGS", _remap_otel_tags),
    "OTEL_SDK_DISABLED": ("DD_TRACE_OTEL_ENABLED", _remap_otel_sdk_config),
}


# https://github.com/open-telemetry/opentelemetry-python/blob/v1.34.1/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py
SUPPORTED_OTEL_ENV_VARS = {
    "OTEL_PYTHON_CONTEXT",
    "OTEL_TRACES_SAMPLER_ARG",
    "OTEL_EXPORTER_OTLP_TIMEOUT",
    "OTEL_EXPORTER_OTLP_PROTOCOL",
    "OTEL_EXPORTER_OTLP_HEADERS",
    "OTEL_EXPORTER_OTLP_ENDPOINT",
    "OTEL_EXPORTER_OTLP_COMPRESSION",
    "OTEL_EXPORTER_OTLP_CERTIFICATE",
    "OTEL_LOGS_EXPORTER",
    "OTEL_EXPORTER_OTLP_LOGS_PROTOCOL",
    "OTEL_EXPORTER_OTLP_LOGS_ENDPOINT",
    "OTEL_EXPORTER_OTLP_LOGS_CLIENT_KEY",
    "OTEL_EXPORTER_OTLP_LOGS_CLIENT_CERTIFICATE",
    "OTEL_EXPORTER_OTLP_LOGS_HEADERS",
    "OTEL_EXPORTER_OTLP_LOGS_INSECURE",
    "OTEL_EXPORTER_OTLP_LOGS_COMPRESSION",
    "OTEL_EXPORTER_OTLP_LOGS_TIMEOUT",
    "OTEL_EXPORTER_OTLP_METRICS_PROTOCOL",
    "OTEL_EXPORTER_OTLP_METRICS_ENDPOINT",
    "OTEL_EXPORTER_OTLP_METRICS_CERTIFICATE",
    "OTEL_EXPORTER_OTLP_METRICS_CLIENT_KEY",
    "OTEL_EXPORTER_OTLP_METRICS_CLIENT_CERTIFICATE",
    "OTEL_EXPORTER_OTLP_METRICS_HEADERS",
    "OTEL_EXPORTER_OTLP_METRICS_INSECURE",
    "OTEL_EXPORTER_OTLP_METRICS_COMPRESSION",
    "OTEL_EXPORTER_OTLP_METRICS_TIMEOUT",
}


def parse_otel_env(otel_env: str) -> tuple[str, Optional[str]]:
    _, otel_config_validator = ENV_VAR_MAPPINGS[otel_env]
    raw_value = os.environ.get(otel_env, "")
    if otel_env not in ("OTEL_RESOURCE_ATTRIBUTES", "OTEL_SERVICE_NAME"):
        # Resource attributes and service name are case-insensitive
        raw_value = raw_value.lower()
    mapped_value = otel_config_validator(raw_value)
    if mapped_value is None:
        return "", None
    return raw_value, mapped_value