#!/usr/bin/env python3
# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
"""Interactive perf list."""

from abc import ABC, abstractmethod
import argparse
from dataclasses import dataclass
import math
from typing import Any, Dict, Optional, Tuple
import perf
from textual import on
from textual.app import App, ComposeResult
from textual.binding import Binding
from textual.containers import Horizontal, HorizontalGroup, Vertical, VerticalScroll
from textual.css.query import NoMatches
from textual.command import SearchIcon
from textual.screen import ModalScreen
from textual.widgets import Button, Footer, Header, Input, Label, Sparkline, Static, Tree
from textual.widgets.tree import TreeNode


def get_info(info: Dict[str, str], key: str):
    return (info[key] + "\n") if key in info else ""


class TreeValue(ABC):
    """Abstraction for the data of value in the tree."""

    @abstractmethod
    def name(self) -> str:
        pass

    @abstractmethod
    def description(self) -> str:
        pass

    @abstractmethod
    def matches(self, query: str) -> bool:
        pass

    @abstractmethod
    def parse(self) -> perf.evlist:
        pass

    @abstractmethod
    def value(self, evlist: perf.evlist, evsel: perf.evsel, cpu: int, thread: int) -> float:
        pass


@dataclass
class Metric(TreeValue):
    """A metric in the tree."""
    metric_name: str

    def name(self) -> str:
        return self.metric_name

    def description(self) -> str:
        """Find and format metric description."""
        for metric in perf.metrics():
            if metric["MetricName"] != self.metric_name:
                continue
            desc = get_info(metric, "BriefDescription")
            desc += get_info(metric, "PublicDescription")
            desc += get_info(metric, "MetricExpr")
            desc += get_info(metric, "MetricThreshold")
            return desc
        return "description"

    def matches(self, query: str) -> bool:
        return query in self.metric_name

    def parse(self) -> perf.evlist:
        return perf.parse_metrics(self.metric_name)

    def value(self, evlist: perf.evlist, evsel: perf.evsel, cpu: int, thread: int) -> float:
        val = evlist.compute_metric(self.metric_name, cpu, thread)
        return 0 if math.isnan(val) else val


@dataclass
class PmuEvent(TreeValue):
    """A PMU and event within the tree."""
    pmu: str
    event: str

    def name(self) -> str:
        if self.event.startswith(self.pmu) or ':' in self.event:
            return self.event
        else:
            return f"{self.pmu}/{self.event}/"

    def description(self) -> str:
        """Find and format event description for {pmu}/{event}/."""
        for p in perf.pmus():
            if p.name() != self.pmu:
                continue
            for info in p.events():
                if "name" not in info or info["name"] != self.event:
                    continue

                desc = get_info(info, "topic")
                desc += get_info(info, "event_type_desc")
                desc += get_info(info, "desc")
                desc += get_info(info, "long_desc")
                desc += get_info(info, "encoding_desc")
                return desc
        return "description"

    def matches(self, query: str) -> bool:
        return query in self.pmu or query in self.event

    def parse(self) -> perf.evlist:
        return perf.parse_events(self.name())

    def value(self, evlist: perf.evlist, evsel: perf.evsel, cpu: int, thread: int) -> float:
        return evsel.read(cpu, thread).val


class ErrorScreen(ModalScreen[bool]):
    """Pop up dialog for errors."""

    CSS = """
    ErrorScreen {
        align: center middle;
    }
    """

    def __init__(self, error: str):
        self.error = error
        super().__init__()

    def compose(self) -> ComposeResult:
        yield Button(f"Error: {self.error}", variant="primary", id="error")

    def on_button_pressed(self, event: Button.Pressed) -> None:
        self.dismiss(True)


class SearchScreen(ModalScreen[str]):
    """Pop up dialog for search."""

    CSS = """
    SearchScreen Horizontal {
        align: center middle;
        margin-top: 1;
    }
    SearchScreen Input {
        width: 1fr;
    }
    """

    def compose(self) -> ComposeResult:
        yield Horizontal(SearchIcon(), Input(placeholder="Event name"))

    def on_input_submitted(self, event: Input.Submitted) -> None:
        """Handle the user pressing Enter in the input field."""
        self.dismiss(event.value)


class Counter(HorizontalGroup):
    """Two labels for a CPU and its counter value."""

    CSS = """
    Label {
        gutter: 1;
    }
    """

    def __init__(self, cpu: int) -> None:
        self.cpu = cpu
        super().__init__()

    def compose(self) -> ComposeResult:
        label = f"cpu{self.cpu}" if self.cpu >= 0 else "total"
        yield Label(label + " ")
        yield Label("0", id=f"counter_{label}")


class CounterSparkline(HorizontalGroup):
    """A Sparkline for a performance counter."""

    def __init__(self, cpu: int) -> None:
        self.cpu = cpu
        super().__init__()

    def compose(self) -> ComposeResult:
        label = f"cpu{self.cpu}" if self.cpu >= 0 else "total"
        yield Label(label)
        yield Sparkline([], summary_function=max, id=f"sparkline_{label}")


class IListApp(App):
    TITLE = "Interactive Perf List"

    BINDINGS = [
        Binding(key="s", action="search", description="Search",
                tooltip="Search events and PMUs"),
        Binding(key="n", action="next", description="Next",
                tooltip="Next search result or item"),
        Binding(key="p", action="prev", description="Previous",
                tooltip="Previous search result or item"),
        Binding(key="c", action="collapse", description="Collapse",
                tooltip="Collapse the current PMU"),
        Binding(key="^q", action="quit", description="Quit",
                tooltip="Quit the app"),
    ]

    CSS = """
        /* Make the 'total' sparkline a different color. */
        #sparkline_total > .sparkline--min-color {
            color: $accent;
        }
        #sparkline_total > .sparkline--max-color {
            color: $accent 30%;
        }
        /*
         * Make the active_search initially not displayed with the text in
         * the middle of the line.
         */
        #active_search {
            display: none;
            width: 100%;
            text-align: center;
        }
    """

    def __init__(self, interval: float) -> None:
        self.interval = interval
        self.evlist = None
        self.selected: Optional[TreeValue] = None
        self.search_results: list[TreeNode[TreeValue]] = []
        self.cur_search_result: TreeNode[TreeValue] | None = None
        super().__init__()

    def expand_and_select(self, node: TreeNode[Any]) -> None:
        """Expand select a node in the tree."""
        if node.parent:
            node.parent.expand()
            if node.parent.parent:
                node.parent.parent.expand()
        node.expand()
        node.tree.select_node(node)
        node.tree.scroll_to_node(node)

    def set_searched_tree_node(self, previous: bool) -> None:
        """Set the cur_search_result node to either the next or previous."""
        l = len(self.search_results)

        if l < 1:
            tree: Tree[TreeValue] = self.query_one("#root", Tree)
            if previous:
                tree.action_cursor_up()
            else:
                tree.action_cursor_down()
            return

        if self.cur_search_result:
            idx = self.search_results.index(self.cur_search_result)
            if previous:
                idx = idx - 1 if idx > 0 else l - 1
            else:
                idx = idx + 1 if idx < l - 1 else 0
        else:
            idx = l - 1 if previous else 0

        node = self.search_results[idx]
        if node == self.cur_search_result:
            return

        self.cur_search_result = node
        self.expand_and_select(node)

    def action_search(self) -> None:
        """Search was chosen."""
        def set_initial_focus(event: str | None) -> None:
            """Sets the focus after the SearchScreen is dismissed."""

            search_label = self.query_one("#active_search", Label)
            search_label.display = True if event else False
            if not event:
                return
            event = event.lower()
            search_label.update(f'Searching for events matching "{event}"')

            tree: Tree[str] = self.query_one("#root", Tree)

            def find_search_results(event: str, node: TreeNode[str],
                                    cursor_seen: bool = False,
                                    match_after_cursor: Optional[TreeNode[str]] = None
                                    ) -> Tuple[bool, Optional[TreeNode[str]]]:
                """Find nodes that match the search remembering the one after the cursor."""
                if not cursor_seen and node == tree.cursor_node:
                    cursor_seen = True
                if node.data and node.data.matches(event):
                    if cursor_seen and not match_after_cursor:
                        match_after_cursor = node
                    self.search_results.append(node)

                if node.children:
                    for child in node.children:
                        (cursor_seen, match_after_cursor) = \
                            find_search_results(event, child, cursor_seen, match_after_cursor)
                return (cursor_seen, match_after_cursor)

            self.search_results.clear()
            (_, self.cur_search_result) = find_search_results(event, tree.root)
            if len(self.search_results) < 1:
                self.push_screen(ErrorScreen(f"Failed to find pmu/event or metric {event}"))
                search_label.display = False
            elif self.cur_search_result:
                self.expand_and_select(self.cur_search_result)
            else:
                self.set_searched_tree_node(previous=False)

        self.push_screen(SearchScreen(), set_initial_focus)

    def action_next(self) -> None:
        """Next was chosen."""
        self.set_searched_tree_node(previous=False)

    def action_prev(self) -> None:
        """Previous was chosen."""
        self.set_searched_tree_node(previous=True)

    def action_collapse(self) -> None:
        """Collapse the part of the tree currently on."""
        tree: Tree[str] = self.query_one("#root", Tree)
        node = tree.cursor_node
        if node and node.parent:
            node.parent.collapse_all()
            node.tree.scroll_to_node(node.parent)

    def update_counts(self) -> None:
        """Called every interval to update counts."""
        if not self.selected or not self.evlist:
            return

        def update_count(cpu: int, count: int):
            # Update the raw count display.
            counter: Label = self.query(f"#counter_cpu{cpu}" if cpu >= 0 else "#counter_total")
            if not counter:
                return
            counter = counter.first(Label)
            counter.update(str(count))

            # Update the sparkline.
            line: Sparkline = self.query(f"#sparkline_cpu{cpu}" if cpu >= 0 else "#sparkline_total")
            if not line:
                return
            line = line.first(Sparkline)
            # If there are more events than the width, remove the front event.
            if len(line.data) > line.size.width:
                line.data.pop(0)
            line.data.append(count)
            line.mutate_reactive(Sparkline.data)

        # Update the total and each CPU counts, assume there's just 1 evsel.
        total = 0
        self.evlist.disable()
        for evsel in self.evlist:
            for cpu in evsel.cpus():
                aggr = 0
                for thread in evsel.threads():
                    aggr += self.selected.value(self.evlist, evsel, cpu, thread)
                update_count(cpu, aggr)
                total += aggr
        update_count(-1, total)
        self.evlist.enable()

    def on_mount(self) -> None:
        """When App starts set up periodic event updating."""
        self.update_counts()
        self.set_interval(self.interval, self.update_counts)

    def set_selected(self, value: TreeValue) -> None:
        """Updates the event/description and starts the counters."""
        try:
            label_name = self.query_one("#event_name", Label)
            event_description = self.query_one("#event_description", Static)
            lines = self.query_one("#lines")
        except NoMatches:
            # A race with rendering, ignore the update as we can't
            # mount the assumed output widgets.
            return

        self.selected = value

        # Remove previous event information.
        if self.evlist:
            self.evlist.disable()
            self.evlist.close()
            old_lines = self.query(CounterSparkline)
            for line in old_lines:
                line.remove()
            old_counters = self.query(Counter)
            for counter in old_counters:
                counter.remove()

        # Update event/metric text and description.
        label_name.update(value.name())
        event_description.update(value.description())

        # Open the event.
        try:
            self.evlist = value.parse()
            if self.evlist:
                self.evlist.open()
                self.evlist.enable()
        except:
            self.evlist = None

        if not self.evlist:
            self.push_screen(ErrorScreen(f"Failed to open {value.name()}"))
            return

        # Add spark lines for all the CPUs. Note, must be done after
        # open so that the evlist CPUs have been computed by propagate
        # maps.
        line = CounterSparkline(cpu=-1)
        lines.mount(line)
        for cpu in self.evlist.all_cpus():
            line = CounterSparkline(cpu)
            lines.mount(line)
        line = Counter(cpu=-1)
        lines.mount(line)
        for cpu in self.evlist.all_cpus():
            line = Counter(cpu)
            lines.mount(line)

    def compose(self) -> ComposeResult:
        """Draws the app."""
        def metric_event_tree() -> Tree:
            """Create tree of PMUs and metricgroups with events or metrics under."""
            tree: Tree[TreeValue] = Tree("Root", id="root")
            pmus = tree.root.add("PMUs")
            for pmu in perf.pmus():
                pmu_name = pmu.name().lower()
                pmu_node = pmus.add(pmu_name)
                try:
                    for event in sorted(pmu.events(), key=lambda x: x["name"]):
                        if "name" in event:
                            e = event["name"].lower()
                            if "alias" in event:
                                pmu_node.add_leaf(f'{e} ({event["alias"]})',
                                                  data=PmuEvent(pmu_name, e))
                            else:
                                pmu_node.add_leaf(e, data=PmuEvent(pmu_name, e))
                except:
                    # Reading events may fail with EPERM, ignore.
                    pass
            metrics = tree.root.add("Metrics")
            groups = set()
            for metric in perf.metrics():
                groups.update(metric["MetricGroup"])

            def add_metrics_to_tree(node: TreeNode[TreeValue], parent: str):
                for metric in sorted(perf.metrics(), key=lambda x: x["MetricName"]):
                    if parent in metric["MetricGroup"]:
                        name = metric["MetricName"]
                        node.add_leaf(name, data=Metric(name))
                        child_group_name = f'{name}_group'
                        if child_group_name in groups:
                            add_metrics_to_tree(node.add(child_group_name), child_group_name)

            for group in sorted(groups):
                if group.endswith('_group'):
                    continue
                add_metrics_to_tree(metrics.add(group), group)

            tree.root.expand()
            return tree

        yield Header(id="header")
        yield Horizontal(Vertical(metric_event_tree(), id="events"),
                         Vertical(Label("event name", id="event_name"),
                                  Static("description", markup=False, id="event_description"),
                                  ))
        yield Label(id="active_search")
        yield VerticalScroll(id="lines")
        yield Footer(id="footer")

    @on(Tree.NodeSelected)
    def on_tree_node_selected(self, event: Tree.NodeSelected[TreeValue]) -> None:
        """Called when a tree node is selected, selecting the event."""
        if event.node.data:
            self.set_selected(event.node.data)


if __name__ == "__main__":
    ap = argparse.ArgumentParser()
    ap.add_argument('-I', '--interval', help="Counter update interval in seconds", default=0.1)
    args = ap.parse_args()
    app = IListApp(float(args.interval))
    app.run()