"""Shader analysis tools: disassemble_shader, get_shader_reflection, get_cbuffer_contents."""

from typing import Optional

from ..session import get_session
from ..util import (
    rd,
    make_error,
    SHADER_STAGE_MAP,
    serialize_shader_variable,
    serialize_sig_element,
)


def _reflection_fallback(stage: str, refl) -> dict:
    result: dict = {
        "stage": stage,
        "source_type": "reflection_only",
        "resource_id": str(refl.resourceId),
        "entry_point": refl.entryPoint,
        "input_signature": [serialize_sig_element(s) for s in refl.inputSignature],
        "output_signature": [serialize_sig_element(s) for s in refl.outputSignature],
        "constant_blocks": [
            {"name": cb.name, "byte_size": cb.byteSize} for cb in refl.constantBlocks
        ],
        "read_only_resources": [
            {"name": ro.name, "type": str(ro.textureType)}
            for ro in refl.readOnlyResources
        ],
        "read_write_resources": [
            {"name": rw.name, "type": str(rw.textureType)}
            for rw in refl.readWriteResources
        ],
        "note": "Disassembly unavailable — showing reflection data only",
    }
    return result


def disassemble_shader(
    stage: str,
    target: Optional[str] = None,
    event_id: Optional[int] = None,
    line_range: Optional[list] = None,
    search: Optional[str] = None,
) -> dict:
    """Disassemble the shader bound at the specified stage.

    If target is omitted, tries all available targets in order and returns the
    first successful result. Falls back to reflection info if all disassembly fails.

    Args:
        stage: Shader stage (vertex, hull, domain, geometry, pixel, compute).
        target: Disassembly target/format. If omitted, tries all available targets.
        event_id: Optional event ID to navigate to first.
        line_range: [start_line, end_line] (1-based). Only return lines in this range.
        search: Keyword to search in the disassembly. Returns matching lines with
                5 lines of context before and after each match.
    """
    session = get_session()
    err = session.require_open()
    if err:
        return err
    err = session.ensure_event(event_id)
    if err:
        return err

    stage_enum = SHADER_STAGE_MAP.get(stage.lower())
    if stage_enum is None:
        return make_error(f"Unknown shader stage: {stage}", "API_ERROR")

    state = session.controller.GetPipelineState()
    refl = state.GetShaderReflection(stage_enum)
    if refl is None:
        return make_error(f"No shader bound at stage '{stage}'", "API_ERROR")

    if stage_enum == rd.ShaderStage.Compute:
        pipe = state.GetComputePipelineObject()
    else:
        pipe = state.GetGraphicsPipelineObject()
    targets = session.controller.GetDisassemblyTargets(True)

    if not targets:
        return _reflection_fallback(stage, refl)

    disasm: Optional[str] = None
    used_target: Optional[str] = None

    if target is not None:
        if target not in targets:
            return make_error(
                f"Unknown disassembly target: {target}. Available: {targets}",
                "API_ERROR",
            )
        disasm = session.controller.DisassembleShader(pipe, refl, target)
        used_target = target
    else:
        for t in targets:
            try:
                d = session.controller.DisassembleShader(pipe, refl, t)
                if d and d.strip():
                    disasm = d
                    used_target = t
                    break
            except Exception:
                continue

    if not disasm:
        result = _reflection_fallback(stage, refl)
        result["available_targets"] = list(targets)
        return result

    all_lines = disasm.splitlines()
    total_lines = len(all_lines)

    if line_range is not None and len(line_range) == 2:
        start = max(1, line_range[0]) - 1
        end = min(total_lines, line_range[1])
        filtered_lines = all_lines[start:end]
        disasm_out = "\n".join(filtered_lines)
        note = f"Showing lines {start + 1}–{end} of {total_lines}"
    elif search is not None:
        kw = search.lower()
        context = 5
        include: set[int] = set()
        for i, line in enumerate(all_lines):
            if kw in line.lower():
                for j in range(max(0, i - context), min(total_lines, i + context + 1)):
                    include.add(j)
        if not include:
            note = f"No matches for '{search}' in {total_lines} lines"
            disasm_out = ""
        else:
            result_lines = []
            prev = -2
            for i in sorted(include):
                if i > prev + 1:
                    result_lines.append("...")
                result_lines.append(f"{i + 1:4d}: {all_lines[i]}")
                prev = i
            disasm_out = "\n".join(result_lines)
            note = f"Found '{search}' in {total_lines} total lines"
    else:
        disasm_out = disasm
        note = None

    result: dict = {
        "stage": stage,
        "target": used_target,
        "available_targets": list(targets),
        "source_type": "disasm",
        "total_lines": total_lines,
        "disassembly": disasm_out,
    }
    if note:
        result["note"] = note
    return result


def get_shader_reflection(
    stage: str,
    event_id: Optional[int] = None,
) -> dict:
    """Get reflection information for the shader at the specified stage.

    Returns input/output signatures, constant buffer layouts, and resource bindings.

    Args:
        stage: Shader stage (vertex, hull, domain, geometry, pixel, compute).
        event_id: Optional event ID to navigate to first.
    """
    session = get_session()
    err = session.require_open()
    if err:
        return err
    err = session.ensure_event(event_id)
    if err:
        return err

    stage_enum = SHADER_STAGE_MAP.get(stage.lower())
    if stage_enum is None:
        return make_error(f"Unknown shader stage: {stage}", "API_ERROR")

    state = session.controller.GetPipelineState()
    refl = state.GetShaderReflection(stage_enum)
    if refl is None:
        return make_error(f"No shader bound at stage '{stage}'", "API_ERROR")

    result: dict = {
        "stage": stage,
        "resource_id": str(refl.resourceId),
        "entry_point": refl.entryPoint,
    }

    result["input_signature"] = [serialize_sig_element(s) for s in refl.inputSignature]
    result["output_signature"] = [
        serialize_sig_element(s) for s in refl.outputSignature
    ]

    cbs = []
    for cb in refl.constantBlocks:
        cbs.append(
            {
                "name": cb.name,
                "byte_size": cb.byteSize,
                "bind_point": cb.fixedBindNumber,
                "variables_count": len(cb.variables),
            }
        )
    result["constant_blocks"] = cbs

    ros = []
    for ro in refl.readOnlyResources:
        ros.append(
            {
                "name": ro.name,
                "type": str(ro.textureType),
                "bind_point": ro.fixedBindNumber,
            }
        )
    result["read_only_resources"] = ros

    rws = []
    for rw in refl.readWriteResources:
        rws.append(
            {
                "name": rw.name,
                "type": str(rw.textureType),
                "bind_point": rw.fixedBindNumber,
            }
        )
    result["read_write_resources"] = rws

    samplers = []
    for s in refl.samplers:
        samplers.append(
            {
                "name": s.name,
                "bind_point": s.fixedBindNumber,
            }
        )
    result["samplers"] = samplers

    return result


def get_cbuffer_contents(
    stage: str,
    cbuffer_index: int,
    event_id: Optional[int] = None,
    filter: Optional[str] = None,
) -> dict:
    """Get the actual values of a constant buffer at the specified shader stage.

    Returns a tree of variable names and their current values.

    Args:
        stage: Shader stage (vertex, hull, domain, geometry, pixel, compute).
        cbuffer_index: Index of the constant buffer (from get_shader_reflection).
        event_id: Optional event ID to navigate to first.
        filter: Case-insensitive substring to match variable names
                (e.g. "ibl", "exposure", "taa", "reflection"). Only matching
                variables are returned.
    """
    session = get_session()
    err = session.require_open()
    if err:
        return err
    err = session.ensure_event(event_id)
    if err:
        return err

    stage_enum = SHADER_STAGE_MAP.get(stage.lower())
    if stage_enum is None:
        return make_error(f"Unknown shader stage: {stage}", "API_ERROR")

    state = session.controller.GetPipelineState()
    refl = state.GetShaderReflection(stage_enum)
    if refl is None:
        return make_error(f"No shader bound at stage '{stage}'", "API_ERROR")

    num_cbs = len(refl.constantBlocks)
    if num_cbs == 0:
        return make_error(
            f"Shader at stage '{stage}' has no constant buffers",
            "API_ERROR",
        )
    if cbuffer_index < 0 or cbuffer_index >= num_cbs:
        return make_error(
            f"cbuffer_index {cbuffer_index} out of range (0-{num_cbs - 1})",
            "API_ERROR",
        )

    if stage_enum == rd.ShaderStage.Compute:
        pipe = state.GetComputePipelineObject()
    else:
        pipe = state.GetGraphicsPipelineObject()
    entry = state.GetShaderEntryPoint(stage_enum)
    cb_bind = state.GetConstantBlock(stage_enum, cbuffer_index, 0)

    cbuffer_vars = session.controller.GetCBufferVariableContents(
        pipe,
        refl.resourceId,
        stage_enum,
        entry,
        cbuffer_index,
        cb_bind.descriptor.resource,
        0,
        0,
    )

    variables = [serialize_shader_variable(v) for v in cbuffer_vars]

    if filter:
        kw = filter.lower()

        def _var_matches(var: dict) -> bool:
            if kw in var.get("name", "").lower():
                return True
            for m in var.get("members", []):
                if _var_matches(m):
                    return True
            return False

        variables = [v for v in variables if _var_matches(v)]

    return {
        "stage": stage,
        "cbuffer_index": cbuffer_index,
        "cbuffer_name": refl.constantBlocks[cbuffer_index].name,
        "filter": filter,
        "variables": variables,
        "variable_count": len(variables),
    }